XXX-XXX Prefer jOOQs fetch().stream() over directly .stream()'ing

See:
- https://maven.apache.org/docs/3.8.7/release-notes.html
- https://github.com/apache/maven/releases/tag/maven-3.8.7
- https://github.com/apache/maven/compare/maven-3.8.6...maven-3.8.7

.github/workflows/build.yaml

@@ -22,11 +22,10 @@ jobs:
             jdk: 17.0.4
             distribution: temurin
             experimental: false
-          # XXX: Re-enable this build after upgrading to Error Prone 2.17.
-          #- os: ubuntu-22.04
-          #  jdk: 20-ea
-          #  distribution: zulu
-          #  experimental: true
+          - os: ubuntu-22.04
+            jdk: 20-ea
+            distribution: zulu
+            experimental: true
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.experimental }}
     steps:

.mvn/maven.config

@@ -1 +1,3 @@
---batch-mode --errors --strict-checksums
+--batch-mode
+--errors
+--strict-checksums

LICENSE.md

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017-2022 Picnic Technologies BV
+Copyright (c) 2017-2023 Picnic Technologies BV
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -36,7 +36,9 @@ code_][picnic-blog-ep-post].
 ### Installation
 
 This library is built on top of [Error Prone][error-prone-orig-repo]. To use
-it:
+it, read the installation guide for Maven or Gradle below.
+
+#### Maven
 
 1. First, follow Error Prone's [installation
    guide][error-prone-installation-guide].
@@ -94,6 +96,31 @@ it:
 Prone Support. Alternatively reference this project's `self-check` profile
 definition. -->
 
+#### Gradle
+
+1. First, follow the [installation guide]
+   [error-prone-gradle-installation-guide] of the `gradle-errorprone-plugin`.
+2. Next, edit your `build.gradle` file to add one or more Error Prone Support
+   modules:
+
+   ```groovy
+   dependencies {
+       // Error Prone itself.
+       errorprone("com.google.errorprone:error_prone_core:${errorProneVersion}")
+       // Error Prone Support's additional bug checkers.
+       errorprone("tech.picnic.error-prone-support:error-prone-contrib:${errorProneSupportVersion}")
+       // Error Prone Support's Refaster rules.
+       errorprone("tech.picnic.error-prone-support:refaster-runner:${errorProneSupportVersion}")
+   }
+
+   tasks.withType(JavaCompile).configureEach {
+       options.errorprone.disableWarningsInGeneratedCode = true
+       // Add other Error Prone flags here. See:
+       // - https://github.com/tbroyer/gradle-errorprone-plugin#configuration
+       // - https://errorprone.info/docs/flags
+   }
+   ```
+
 ### Seeing it in action
 
 Consider the following example code:
@@ -207,6 +234,7 @@ guidelines][contributing].
 [error-prone-bugchecker]: https://github.com/google/error-prone/blob/master/check_api/src/main/java/com/google/errorprone/bugpatterns/BugChecker.java
 [error-prone-fork-jitpack]: https://jitpack.io/#PicnicSupermarket/error-prone
 [error-prone-fork-repo]: https://github.com/PicnicSupermarket/error-prone
+[error-prone-gradle-installation-guide]: https://github.com/tbroyer/gradle-errorprone-plugin
 [error-prone-installation-guide]: https://errorprone.info/docs/installation#maven
 [error-prone-orig-repo]: https://github.com/google/error-prone
 [error-prone-pull-3301]: https://github.com/google/error-prone/pull/3301

apply-error-prone-suggestions.sh

@@ -9,13 +9,14 @@
 set -e -u -o pipefail
 
 if [ "${#}" -gt 1 ]; then
-  echo "Usage: ./$(basename "${0}") [PatchChecks]"
+  echo "Usage: ${0} [PatchChecks]"
   exit 1
 fi
 
 patchChecks=${1:-}
 
 mvn clean test-compile fmt:format \
+  -s "$(dirname "${0}")/settings.xml" \
   -T 1.0C \
   -Perror-prone \
   -Perror-prone-fork \

documentation-support/pom.xml

@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>tech.picnic.error-prone-support</groupId>
+        <artifactId>error-prone-support</artifactId>
+        <version>0.8.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>documentation-support</artifactId>
+
+    <name>Picnic :: Error Prone Support :: Documentation Support</name>
+    <description>Data extraction support for the purpose of documentation generation.</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_annotation</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_check_api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>${groupId.error-prone}</groupId>
+            <artifactId>error_prone_test_helpers</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-annotations</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto</groupId>
+            <artifactId>auto-common</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto.service</groupId>
+            <artifactId>auto-service-annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto.value</groupId>
+            <artifactId>auto-value-annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jspecify</groupId>
+            <artifactId>jspecify</artifactId>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

documentation-support/src/main/java/tech/picnic/errorprone/documentation/BugPatternExtractor.java

@@ -0,0 +1,103 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.base.Verify.verify;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static java.util.Objects.requireNonNull;
+
+import com.google.auto.common.AnnotationMirrors;
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.BugPattern.SeverityLevel;
+import com.google.errorprone.annotations.Immutable;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.AnnotationTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.tools.javac.code.Attribute;
+import com.sun.tools.javac.code.Symbol.ClassSymbol;
+import com.sun.tools.javac.util.Context;
+import javax.lang.model.element.AnnotationValue;
+import tech.picnic.errorprone.documentation.BugPatternExtractor.BugPatternDocumentation;
+
+/**
+ * An {@link Extractor} that describes how to extract data from a {@code @BugPattern} annotation.
+ */
+@Immutable
+final class BugPatternExtractor implements Extractor<BugPatternDocumentation> {
+  @Override
+  public BugPatternDocumentation extract(ClassTree tree, Context context) {
+    ClassSymbol symbol = ASTHelpers.getSymbol(tree);
+    BugPattern annotation = symbol.getAnnotation(BugPattern.class);
+    requireNonNull(annotation, "BugPattern annotation must be present");
+
+    return new AutoValue_BugPatternExtractor_BugPatternDocumentation(
+        symbol.getQualifiedName().toString(),
+        annotation.name().isEmpty() ? tree.getSimpleName().toString() : annotation.name(),
+        ImmutableList.copyOf(annotation.altNames()),
+        annotation.link(),
+        ImmutableList.copyOf(annotation.tags()),
+        annotation.summary(),
+        annotation.explanation(),
+        annotation.severity(),
+        annotation.disableable(),
+        annotation.documentSuppression() ? getSuppressionAnnotations(tree) : ImmutableList.of());
+  }
+
+  @Override
+  public boolean canExtract(ClassTree tree) {
+    return ASTHelpers.hasDirectAnnotationWithSimpleName(tree, BugPattern.class.getSimpleName());
+  }
+
+  /**
+   * Returns the fully-qualified class names of suppression annotations specified by the {@link
+   * BugPattern} annotation located on the given tree.
+   *
+   * @implNote This method cannot simply invoke {@link BugPattern#suppressionAnnotations()}, as that
+   *     will yield an "Attempt to access Class objects for TypeMirrors" exception.
+   */
+  private static ImmutableList<String> getSuppressionAnnotations(ClassTree tree) {
+    AnnotationTree annotationTree =
+        ASTHelpers.getAnnotationWithSimpleName(
+            ASTHelpers.getAnnotations(tree), BugPattern.class.getSimpleName());
+    requireNonNull(annotationTree, "BugPattern annotation must be present");
+
+    Attribute.Array types =
+        doCast(
+            AnnotationMirrors.getAnnotationValue(
+                ASTHelpers.getAnnotationMirror(annotationTree), "suppressionAnnotations"),
+            Attribute.Array.class);
+
+    return types.getValue().stream()
+        .map(v -> doCast(v, Attribute.Class.class).classType.toString())
+        .collect(toImmutableList());
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <T extends AnnotationValue> T doCast(AnnotationValue value, Class<T> target) {
+    verify(target.isInstance(value), "Value '%s' is not of type '%s'", value, target);
+    return (T) value;
+  }
+
+  @AutoValue
+  abstract static class BugPatternDocumentation {
+    abstract String fullyQualifiedName();
+
+    abstract String name();
+
+    abstract ImmutableList<String> altNames();
+
+    abstract String link();
+
+    abstract ImmutableList<String> tags();
+
+    abstract String summary();
+
+    abstract String explanation();
+
+    abstract SeverityLevel severityLevel();
+
+    abstract boolean canDisable();
+
+    abstract ImmutableList<String> suppressionAnnotations();
+  }
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/DocumentationGenerator.java

@@ -0,0 +1,56 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.auto.service.AutoService;
+import com.google.common.annotations.VisibleForTesting;
+import com.sun.source.util.JavacTask;
+import com.sun.source.util.Plugin;
+import com.sun.tools.javac.api.BasicJavacTask;
+import java.nio.file.InvalidPathException;
+import java.nio.file.Path;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * A compiler {@link Plugin} that analyzes and extracts relevant information for documentation
+ * purposes from processed files.
+ */
+// XXX: Find a better name for this class; it doesn't generate documentation per se.
+@AutoService(Plugin.class)
+public final class DocumentationGenerator implements Plugin {
+  @VisibleForTesting static final String OUTPUT_DIRECTORY_FLAG = "-XoutputDirectory";
+  private static final Pattern OUTPUT_DIRECTORY_FLAG_PATTERN =
+      Pattern.compile(Pattern.quote(OUTPUT_DIRECTORY_FLAG) + "=(.*)");
+
+  /** Instantiates a new {@link DocumentationGenerator} instance. */
+  public DocumentationGenerator() {}
+
+  @Override
+  public String getName() {
+    return getClass().getSimpleName();
+  }
+
+  @Override
+  public void init(JavacTask javacTask, String... args) {
+    checkArgument(args.length == 1, "Precisely one path must be provided");
+
+    javacTask.addTaskListener(
+        new DocumentationGeneratorTaskListener(
+            ((BasicJavacTask) javacTask).getContext(), getOutputPath(args[0])));
+  }
+
+  @VisibleForTesting
+  static Path getOutputPath(String pathArg) {
+    Matcher matcher = OUTPUT_DIRECTORY_FLAG_PATTERN.matcher(pathArg);
+    checkArgument(
+        matcher.matches(), "'%s' must be of the form '%s=<value>'", pathArg, OUTPUT_DIRECTORY_FLAG);
+
+    String path = matcher.group(1);
+    try {
+      return Path.of(path);
+    } catch (InvalidPathException e) {
+      throw new IllegalArgumentException(String.format("Invalid path '%s'", path), e);
+    }
+  }
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/DocumentationGeneratorTaskListener.java

@@ -0,0 +1,91 @@
+package tech.picnic.errorprone.documentation;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.util.TaskEvent;
+import com.sun.source.util.TaskEvent.Kind;
+import com.sun.source.util.TaskListener;
+import com.sun.tools.javac.api.JavacTrees;
+import com.sun.tools.javac.util.Context;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.URI;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import javax.tools.JavaFileObject;
+
+/**
+ * A {@link TaskListener} that identifies and extracts relevant content for documentation generation
+ * and writes it to disk.
+ */
+// XXX: Find a better name for this class; it doesn't generate documentation per se.
+final class DocumentationGeneratorTaskListener implements TaskListener {
+  private static final ObjectMapper OBJECT_MAPPER =
+      new ObjectMapper().setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
+
+  private final Context context;
+  private final Path docsPath;
+
+  DocumentationGeneratorTaskListener(Context context, Path path) {
+    this.context = context;
+    this.docsPath = path;
+  }
+
+  @Override
+  public void started(TaskEvent taskEvent) {
+    if (taskEvent.getKind() == Kind.ANALYZE) {
+      createDocsDirectory();
+    }
+  }
+
+  @Override
+  public void finished(TaskEvent taskEvent) {
+    if (taskEvent.getKind() != Kind.ANALYZE) {
+      return;
+    }
+
+    ClassTree classTree = JavacTrees.instance(context).getTree(taskEvent.getTypeElement());
+    JavaFileObject sourceFile = taskEvent.getSourceFile();
+    if (classTree == null || sourceFile == null) {
+      return;
+    }
+
+    ExtractorType.findMatchingType(classTree)
+        .ifPresent(
+            extractorType ->
+                writeToFile(
+                    extractorType.getIdentifier(),
+                    getSimpleClassName(sourceFile.toUri()),
+                    extractorType.getExtractor().extract(classTree, context)));
+  }
+
+  private void createDocsDirectory() {
+    try {
+      Files.createDirectories(docsPath);
+    } catch (IOException e) {
+      throw new IllegalStateException(
+          String.format("Error while creating directory with path '%s'", docsPath), e);
+    }
+  }
+
+  private <T> void writeToFile(String identifier, String className, T data) {
+    File file = docsPath.resolve(String.format("%s-%s.json", identifier, className)).toFile();
+
+    try (FileWriter fileWriter = new FileWriter(file, UTF_8)) {
+      OBJECT_MAPPER.writeValue(fileWriter, data);
+    } catch (IOException e) {
+      throw new UncheckedIOException(String.format("Cannot write to file '%s'", file.getPath()), e);
+    }
+  }
+
+  private static String getSimpleClassName(URI path) {
+    return Paths.get(path).getFileName().toString().replace(".java", "");
+  }
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/Extractor.java

@@ -0,0 +1,33 @@
+package tech.picnic.errorprone.documentation;
+
+import com.google.errorprone.annotations.Immutable;
+import com.sun.source.tree.ClassTree;
+import com.sun.tools.javac.util.Context;
+
+/**
+ * Interface implemented by classes that define how to extract data of some type {@link T} from a
+ * given {@link ClassTree}.
+ *
+ * @param <T> The type of data that is extracted.
+ */
+@Immutable
+interface Extractor<T> {
+  /**
+   * Extracts and returns an instance of {@link T} using the provided arguments.
+   *
+   * @param tree The {@link ClassTree} to analyze and from which to extract instances of {@link T}.
+   * @param context The {@link Context} in which the current compilation takes place.
+   * @return A non-null instance of {@link T}.
+   */
+  // XXX: Drop `Context` parameter unless used.
+  T extract(ClassTree tree, Context context);
+
+  /**
+   * Tells whether this {@link Extractor} can extract documentation content from the given {@link
+   * ClassTree}.
+   *
+   * @param tree The {@link ClassTree} of interest.
+   * @return {@code true} iff data extraction is supported.
+   */
+  boolean canExtract(ClassTree tree);
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/ExtractorType.java

@@ -0,0 +1,35 @@
+package tech.picnic.errorprone.documentation;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import com.sun.source.tree.ClassTree;
+import java.util.EnumSet;
+import java.util.Optional;
+
+/** An enumeration of {@link Extractor} types. */
+enum ExtractorType {
+  BUG_PATTERN("bugpattern", new BugPatternExtractor());
+
+  private static final ImmutableSet<ExtractorType> TYPES =
+      Sets.immutableEnumSet(EnumSet.allOf(ExtractorType.class));
+
+  private final String identifier;
+  private final Extractor<?> extractor;
+
+  ExtractorType(String identifier, Extractor<?> extractor) {
+    this.identifier = identifier;
+    this.extractor = extractor;
+  }
+
+  String getIdentifier() {
+    return identifier;
+  }
+
+  Extractor<?> getExtractor() {
+    return extractor;
+  }
+
+  static Optional<ExtractorType> findMatchingType(ClassTree tree) {
+    return TYPES.stream().filter(type -> type.getExtractor().canExtract(tree)).findFirst();
+  }
+}

documentation-support/src/main/java/tech/picnic/errorprone/documentation/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * A Java compiler plugin that extracts data from compiled classes, in support of the Error Prone
+ * Support documentation.
+ */
+@com.google.errorprone.annotations.CheckReturnValue
+@org.jspecify.annotations.NullMarked
+package tech.picnic.errorprone.documentation;

documentation-support/src/test/java/tech/picnic/errorprone/documentation/BugPatternExtractorTest.java

@@ -0,0 +1,153 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.google.common.io.Resources;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.CompilationTestHelper;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.sun.source.tree.ClassTree;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+final class BugPatternExtractorTest {
+  @Test
+  void noBugPattern(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "TestCheckerWithoutAnnotation.java",
+        "import com.google.errorprone.bugpatterns.BugChecker;",
+        "",
+        "public final class TestCheckerWithoutAnnotation extends BugChecker {}");
+
+    assertThat(outputDirectory.toAbsolutePath()).isEmptyDirectory();
+  }
+
+  @Test
+  void minimalBugPattern(@TempDir Path outputDirectory) throws IOException {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "MinimalBugChecker.java",
+        "package pkg;",
+        "",
+        "import com.google.errorprone.BugPattern;",
+        "import com.google.errorprone.BugPattern.SeverityLevel;",
+        "import com.google.errorprone.bugpatterns.BugChecker;",
+        "",
+        "@BugPattern(summary = \"MinimalBugChecker summary\", severity = SeverityLevel.ERROR)",
+        "public final class MinimalBugChecker extends BugChecker {}");
+
+    verifyFileMatchesResource(
+        outputDirectory,
+        "bugpattern-MinimalBugChecker.json",
+        "bugpattern-documentation-minimal.json");
+  }
+
+  @Test
+  void completeBugPattern(@TempDir Path outputDirectory) throws IOException {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "CompleteBugChecker.java",
+        "package pkg;",
+        "",
+        "import com.google.errorprone.BugPattern;",
+        "import com.google.errorprone.BugPattern.SeverityLevel;",
+        "import com.google.errorprone.bugpatterns.BugChecker;",
+        "import org.junit.jupiter.api.Test;",
+        "",
+        "@BugPattern(",
+        "    name = \"OtherName\",",
+        "    summary = \"CompleteBugChecker summary\",",
+        "    linkType = BugPattern.LinkType.CUSTOM,",
+        "    link = \"https://error-prone.picnic.tech\",",
+        "    explanation = \"Example explanation\",",
+        "    severity = SeverityLevel.SUGGESTION,",
+        "    altNames = \"Check\",",
+        "    tags = BugPattern.StandardTags.SIMPLIFICATION,",
+        "    disableable = false,",
+        "    suppressionAnnotations = {BugPattern.class, Test.class})",
+        "public final class CompleteBugChecker extends BugChecker {}");
+
+    verifyFileMatchesResource(
+        outputDirectory,
+        "bugpattern-CompleteBugChecker.json",
+        "bugpattern-documentation-complete.json");
+  }
+
+  @Test
+  void undocumentedSuppressionBugPattern(@TempDir Path outputDirectory) throws IOException {
+    Compilation.compileWithDocumentationGenerator(
+        outputDirectory,
+        "UndocumentedSuppressionBugPattern.java",
+        "package pkg;",
+        "",
+        "import com.google.errorprone.BugPattern;",
+        "import com.google.errorprone.BugPattern.SeverityLevel;",
+        "import com.google.errorprone.bugpatterns.BugChecker;",
+        "",
+        "@BugPattern(",
+        "    summary = \"UndocumentedSuppressionBugPattern summary\",",
+        "    severity = SeverityLevel.WARNING,",
+        "    documentSuppression = false)",
+        "public final class UndocumentedSuppressionBugPattern extends BugChecker {}");
+
+    verifyFileMatchesResource(
+        outputDirectory,
+        "bugpattern-UndocumentedSuppressionBugPattern.json",
+        "bugpattern-documentation-undocumented-suppression.json");
+  }
+
+  @Test
+  void bugPatternAnnotationIsAbsent() {
+    CompilationTestHelper.newInstance(TestChecker.class, getClass())
+        .addSourceLines(
+            "TestChecker.java",
+            "import com.google.errorprone.bugpatterns.BugChecker;",
+            "",
+            "// BUG: Diagnostic contains: Can extract: false",
+            "public final class TestChecker extends BugChecker {}")
+        .doTest();
+  }
+
+  private static void verifyFileMatchesResource(
+      Path outputDirectory, String fileName, String resourceName) throws IOException {
+    assertThat(Files.readString(outputDirectory.resolve(fileName)))
+        .isEqualToIgnoringWhitespace(getResource(resourceName));
+  }
+
+  // XXX: Once we support only JDK 15+, drop this method in favour of including the resources as
+  // text blocks in this class. (This also requires renaming the `verifyFileMatchesResource`
+  // method.)
+  private static String getResource(String resourceName) throws IOException {
+    return Resources.toString(
+        Resources.getResource(BugPatternExtractorTest.class, resourceName), UTF_8);
+  }
+
+  /** A {@link BugChecker} that validates the {@link BugPatternExtractor}. */
+  @BugPattern(summary = "Validates `BugPatternExtractor` extraction", severity = ERROR)
+  public static final class TestChecker extends BugChecker implements ClassTreeMatcher {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public Description matchClass(ClassTree tree, VisitorState state) {
+      BugPatternExtractor extractor = new BugPatternExtractor();
+
+      assertThatThrownBy(() -> extractor.extract(tree, state.context))
+          .isInstanceOf(NullPointerException.class)
+          .hasMessage("BugPattern annotation must be present");
+
+      return buildDescription(tree)
+          .setMessage(String.format("Can extract: %s", extractor.canExtract(tree)))
+          .build();
+    }
+  }
+}

documentation-support/src/test/java/tech/picnic/errorprone/documentation/Compilation.java

@@ -0,0 +1,45 @@
+package tech.picnic.errorprone.documentation;
+
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.FileManagers;
+import com.google.errorprone.FileObjects;
+import com.sun.tools.javac.api.JavacTaskImpl;
+import com.sun.tools.javac.api.JavacTool;
+import com.sun.tools.javac.file.JavacFileManager;
+import java.nio.file.Path;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+
+// XXX: Generalize and move this class so that it can also be used by `refaster-compiler`.
+// XXX: Add support for this class to the `ErrorProneTestHelperSourceFormat` check.
+public final class Compilation {
+  private Compilation() {}
+
+  public static void compileWithDocumentationGenerator(
+      Path outputDirectory, String fileName, String... lines) {
+    compileWithDocumentationGenerator(outputDirectory.toAbsolutePath().toString(), fileName, lines);
+  }
+
+  public static void compileWithDocumentationGenerator(
+      String outputDirectory, String fileName, String... lines) {
+    compile(
+        ImmutableList.of("-Xplugin:DocumentationGenerator -XoutputDirectory=" + outputDirectory),
+        FileObjects.forSourceLines(fileName, lines));
+  }
+
+  private static void compile(ImmutableList<String> options, JavaFileObject javaFileObject) {
+    JavacFileManager javacFileManager = FileManagers.testFileManager();
+    JavaCompiler compiler = JavacTool.create();
+    JavacTaskImpl task =
+        (JavacTaskImpl)
+            compiler.getTask(
+                null,
+                javacFileManager,
+                null,
+                options,
+                ImmutableList.of(),
+                ImmutableList.of(javaFileObject));
+
+    task.call();
+  }
+}

documentation-support/src/test/java/tech/picnic/errorprone/documentation/DocumentationGeneratorTaskListenerTest.java

@@ -0,0 +1,77 @@
+package tech.picnic.errorprone.documentation;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static java.nio.file.attribute.AclEntryPermission.ADD_SUBDIRECTORY;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.jupiter.api.condition.OS.WINDOWS;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+import java.io.IOException;
+import java.nio.file.FileSystemException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.AclEntry;
+import java.nio.file.attribute.AclFileAttributeView;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.DisabledOnOs;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.io.TempDir;
+
+final class DocumentationGeneratorTaskListenerTest {
+  @EnabledOnOs(WINDOWS)
+  @Test
+  void readOnlyFileSystemWindows(@TempDir Path outputDirectory) throws IOException {
+    AclFileAttributeView view =
+        Files.getFileAttributeView(outputDirectory, AclFileAttributeView.class);
+    view.setAcl(
+        view.getAcl().stream()
+            .map(
+                entry ->
+                    AclEntry.newBuilder(entry)
+                        .setPermissions(
+                            Sets.difference(entry.permissions(), ImmutableSet.of(ADD_SUBDIRECTORY)))
+                        .build())
+            .collect(toImmutableList()));
+
+    readOnlyFileSystemFailsToWrite(outputDirectory.resolve("nonexistent"));
+  }
+
+  @DisabledOnOs(WINDOWS)
+  @Test
+  void readOnlyFileSystemNonWindows(@TempDir Path outputDirectory) {
+    assertThat(outputDirectory.toFile().setWritable(false))
+        .describedAs("Failed to make test directory unwritable")
+        .isTrue();
+
+    readOnlyFileSystemFailsToWrite(outputDirectory.resolve("nonexistent"));
+  }
+
+  private static void readOnlyFileSystemFailsToWrite(Path outputDirectory) {
+    assertThatThrownBy(
+            () ->
+                Compilation.compileWithDocumentationGenerator(
+                    outputDirectory, "A.java", "class A {}"))
+        .hasRootCauseInstanceOf(FileSystemException.class)
+        .hasCauseInstanceOf(IllegalStateException.class)
+        .hasMessageEndingWith("Error while creating directory with path '%s'", outputDirectory);
+  }
+
+  @Test
+  void noClassNoOutput(@TempDir Path outputDirectory) {
+    Compilation.compileWithDocumentationGenerator(outputDirectory, "A.java", "package pkg;");
+
+    assertThat(outputDirectory).isEmptyDirectory();
+  }
+
+  @Test
+  void excessArguments(@TempDir Path outputDirectory) {
+    assertThatThrownBy(
+            () ->
+                Compilation.compileWithDocumentationGenerator(
+                    outputDirectory.toAbsolutePath() + " extra-arg", "A.java", "package pkg;"))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("Precisely one path must be provided");
+  }
+}

documentation-support/src/test/java/tech/picnic/errorprone/documentation/DocumentationGeneratorTest.java

@@ -0,0 +1,38 @@
+package tech.picnic.errorprone.documentation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static tech.picnic.errorprone.documentation.DocumentationGenerator.OUTPUT_DIRECTORY_FLAG;
+
+import java.nio.file.InvalidPathException;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+final class DocumentationGeneratorTest {
+  @ParameterizedTest
+  @ValueSource(strings = {"bar", "foo"})
+  void getOutputPath(String path) {
+    assertThat(DocumentationGenerator.getOutputPath(OUTPUT_DIRECTORY_FLAG + '=' + path))
+        .isEqualTo(Path.of(path));
+  }
+
+  @ParameterizedTest
+  @ValueSource(strings = {"", "-XoutputDirectory", "invalidOption=Test", "nothing"})
+  void getOutputPathWithInvalidArgument(String pathArg) {
+    assertThatThrownBy(() -> DocumentationGenerator.getOutputPath(pathArg))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("'%s' must be of the form '%s=<value>'", pathArg, OUTPUT_DIRECTORY_FLAG);
+  }
+
+  @Test
+  void getOutputPathWithInvalidPath() {
+    String basePath = "path-with-null-char-\0";
+    assertThatThrownBy(
+            () -> DocumentationGenerator.getOutputPath(OUTPUT_DIRECTORY_FLAG + '=' + basePath))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasCauseInstanceOf(InvalidPathException.class)
+        .hasMessageEndingWith("Invalid path '%s'", basePath);
+  }
+}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/bugpattern-documentation-complete.json

@@ -0,0 +1,19 @@
+{
+  "fullyQualifiedName": "pkg.CompleteBugChecker",
+  "name": "OtherName",
+  "altNames": [
+    "Check"
+  ],
+  "link": "https://error-prone.picnic.tech",
+  "tags": [
+    "Simplification"
+  ],
+  "summary": "CompleteBugChecker summary",
+  "explanation": "Example explanation",
+  "severityLevel": "SUGGESTION",
+  "canDisable": false,
+  "suppressionAnnotations": [
+    "com.google.errorprone.BugPattern",
+    "org.junit.jupiter.api.Test"
+  ]
+}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/bugpattern-documentation-minimal.json

@@ -0,0 +1,14 @@
+{
+  "fullyQualifiedName": "pkg.MinimalBugChecker",
+  "name": "MinimalBugChecker",
+  "altNames": [],
+  "link": "",
+  "tags": [],
+  "summary": "MinimalBugChecker summary",
+  "explanation": "",
+  "severityLevel": "ERROR",
+  "canDisable": true,
+  "suppressionAnnotations": [
+    "java.lang.SuppressWarnings"
+  ]
+}

documentation-support/src/test/resources/tech/picnic/errorprone/documentation/bugpattern-documentation-undocumented-suppression.json

@@ -0,0 +1,12 @@
+{
+  "fullyQualifiedName": "pkg.UndocumentedSuppressionBugPattern",
+  "name": "UndocumentedSuppressionBugPattern",
+  "altNames": [],
+  "link": "",
+  "tags": [],
+  "summary": "UndocumentedSuppressionBugPattern summary",
+  "explanation": "",
+  "severityLevel": "WARNING",
+  "canDisable": true,
+  "suppressionAnnotations": []
+}

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.6.1-SNAPSHOT</version>
+        <version>0.8.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -39,6 +39,14 @@
             <artifactId>error_prone_test_helpers</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>${project.groupId}</groupId>
+            <artifactId>documentation-support</artifactId>
+            <!-- This dependency is declared only as a hint to Maven that
+            compilation depends on it; see the `maven-compiler-plugin`'s
+            `annotationProcessorPaths` configuration below. -->
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>refaster-support</artifactId>
@@ -138,6 +146,10 @@
             <artifactId>value-annotations</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.jooq</groupId>
+            <artifactId>jooq</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.jspecify</groupId>
             <artifactId>jspecify</artifactId>
@@ -146,7 +158,7 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
-            <scope>test</scope>
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
@@ -213,6 +225,11 @@
                     <artifactId>maven-compiler-plugin</artifactId>
                     <configuration>
                         <annotationProcessorPaths combine.children="append">
+                            <path>
+                                <groupId>${project.groupId}</groupId>
+                                <artifactId>documentation-support</artifactId>
+                                <version>${project.version}</version>
+                            </path>
                             <path>
                                 <groupId>${project.groupId}</groupId>
                                 <artifactId>refaster-compiler</artifactId>
@@ -226,6 +243,7 @@
                         </annotationProcessorPaths>
                         <compilerArgs combine.children="append">
                             <arg>-Xplugin:RefasterRuleCompiler</arg>
+                            <arg>-Xplugin:DocumentationGenerator -XoutputDirectory=${project.build.directory}/docs</arg>
                         </compilerArgs>
                     </configuration>
                 </plugin>

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclaration.java

@@ -9,7 +9,6 @@ import static com.google.errorprone.matchers.Matchers.hasModifier;
 import static com.google.errorprone.matchers.Matchers.not;
 import static java.util.function.Predicate.not;
 import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
-import static tech.picnic.errorprone.bugpatterns.util.JavaKeywords.isValidIdentifier;
 import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.SETUP_OR_TEARDOWN_METHOD;
 import static tech.picnic.errorprone.bugpatterns.util.MoreJUnitMatchers.TEST_METHOD;
 
@@ -25,15 +24,11 @@ import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.util.ASTHelpers;
-import com.sun.source.tree.ImportTree;
 import com.sun.source.tree.MethodTree;
-import com.sun.source.tree.Tree;
-import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Symbol.MethodSymbol;
-import com.sun.tools.javac.code.Type;
 import java.util.Optional;
 import javax.lang.model.element.Modifier;
-import tech.picnic.errorprone.bugpatterns.util.SourceCode;
+import tech.picnic.errorprone.bugpatterns.util.ConflictDetection;
 
 /** A {@link BugChecker} that flags non-canonical JUnit method declarations. */
 // XXX: Consider introducing a class-level check that enforces that test classes:
@@ -90,7 +85,7 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
     tryCanonicalizeMethodName(symbol)
         .ifPresent(
             newName ->
-                findMethodRenameBlocker(symbol, newName, state)
+                ConflictDetection.findMethodRenameBlocker(symbol, newName, state)
                     .ifPresentOrElse(
                         blocker -> reportMethodRenameBlocker(tree, blocker, state),
                         () -> fixBuilder.merge(SuggestedFixes.renameMethod(tree, newName, state))));
@@ -106,61 +101,7 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
             .build());
   }
 
-  /**
-   * If applicable, returns a human-readable argument against assigning the given name to an
-   * existing method.
-   *
-   * <p>This method implements imperfect heuristics. Things it currently does not consider include
-   * the following:
-   *
-   * <ul>
-   *   <li>Whether the rename would merely introduce a method overload, rather than clashing with an
-   *       existing method declaration.
-   *   <li>Whether the rename would cause a method in a superclass to be overridden.
-   *   <li>Whether the rename would in fact clash with a static import. (It could be that a static
-   *       import of the same name is only referenced from lexical scopes in which the method under
-   *       consideration cannot be referenced directly.)
-   * </ul>
-   */
-  private static Optional<String> findMethodRenameBlocker(
-      MethodSymbol method, String newName, VisitorState state) {
-    if (isExistingMethodName(method.owner.type, newName, state)) {
-      return Optional.of(
-          String.format(
-              "a method named `%s` is already defined in this class or a supertype", newName));
-    }
-
-    if (isSimpleNameStaticallyImported(newName, state)) {
-      return Optional.of(String.format("`%s` is already statically imported", newName));
-    }
-
-    if (!isValidIdentifier(newName)) {
-      return Optional.of(String.format("`%s` is not a valid identifier", newName));
-    }
-
-    return Optional.empty();
-  }
-
-  private static boolean isExistingMethodName(Type clazz, String name, VisitorState state) {
-    return ASTHelpers.matchingMethods(state.getName(name), method -> true, clazz, state.getTypes())
-        .findAny()
-        .isPresent();
-  }
-
-  private static boolean isSimpleNameStaticallyImported(String simpleName, VisitorState state) {
-    return state.getPath().getCompilationUnit().getImports().stream()
-        .filter(ImportTree::isStatic)
-        .map(ImportTree::getQualifiedIdentifier)
-        .map(tree -> getStaticImportSimpleName(tree, state))
-        .anyMatch(simpleName::contentEquals);
-  }
-
-  private static CharSequence getStaticImportSimpleName(Tree tree, VisitorState state) {
-    String source = SourceCode.treeToString(tree, state);
-    return source.subSequence(source.lastIndexOf('.') + 1, source.length());
-  }
-
-  private static Optional<String> tryCanonicalizeMethodName(Symbol symbol) {
+  private static Optional<String> tryCanonicalizeMethodName(MethodSymbol symbol) {
     return Optional.of(symbol.getQualifiedName().toString())
         .filter(name -> name.startsWith(TEST_PREFIX))
         .map(name -> name.substring(TEST_PREFIX.length()))

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListing.java

@@ -42,6 +42,7 @@ import java.util.Set;
 import java.util.stream.Stream;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
+import tech.picnic.errorprone.bugpatterns.util.Flags;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
@@ -220,7 +221,7 @@ public final class LexicographicalAnnotationAttributeListing extends BugChecker
 
   private static ImmutableList<String> excludedAnnotations(ErrorProneFlags flags) {
     Set<String> exclusions = new HashSet<>();
-    flags.getList(EXCLUDED_ANNOTATIONS_FLAG).ifPresent(exclusions::addAll);
+    exclusions.addAll(Flags.getList(flags, EXCLUDED_ANNOTATIONS_FLAG));
     exclusions.addAll(BLACKLISTED_ANNOTATIONS);
     return ImmutableList.copyOf(exclusions);
   }

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversion.java

@@ -49,6 +49,7 @@ import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Stream;
+import tech.picnic.errorprone.bugpatterns.util.Flags;
 import tech.picnic.errorprone.bugpatterns.util.MethodMatcherFactory;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
@@ -63,9 +64,8 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 public final class RedundantStringConversion extends BugChecker
     implements BinaryTreeMatcher, CompoundAssignmentTreeMatcher, MethodInvocationTreeMatcher {
   private static final long serialVersionUID = 1L;
-  private static final String FLAG_PREFIX = "RedundantStringConversion:";
   private static final String EXTRA_STRING_CONVERSION_METHODS_FLAG =
-      FLAG_PREFIX + "ExtraConversionMethods";
+      "RedundantStringConversion:ExtraConversionMethods";
 
   @SuppressWarnings("UnnecessaryLambda")
   private static final Matcher<ExpressionTree> ANY_EXPR = (t, s) -> true;
@@ -374,10 +374,9 @@ public final class RedundantStringConversion extends BugChecker
       ErrorProneFlags flags) {
     // XXX: ErrorProneFlags#getList splits by comma, but method signatures may also contain commas.
     // For this class methods accepting more than one argument are not valid, but still: not nice.
-    return flags
-        .getList(EXTRA_STRING_CONVERSION_METHODS_FLAG)
-        .map(new MethodMatcherFactory()::create)
-        .map(m -> anyOf(WELL_KNOWN_STRING_CONVERSION_METHODS, m))
-        .orElse(WELL_KNOWN_STRING_CONVERSION_METHODS);
+    return anyOf(
+        WELL_KNOWN_STRING_CONVERSION_METHODS,
+        new MethodMatcherFactory()
+            .create(Flags.getList(flags, EXTRA_STRING_CONVERSION_METHODS_FLAG)));
   }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/RequestParamType.java

@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.bugpatterns;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
 import static com.google.errorprone.BugPattern.StandardTags.LIKELY_ERROR;
@@ -9,41 +10,72 @@ import static com.google.errorprone.matchers.Matchers.annotations;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.isSubtypeOf;
 import static com.google.errorprone.matchers.Matchers.isType;
+import static com.google.errorprone.matchers.Matchers.not;
 import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.BugPattern;
+import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.suppliers.Suppliers;
+import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
+import tech.picnic.errorprone.bugpatterns.util.Flags;
 
 /** A {@link BugChecker} that flags {@code @RequestParam} parameters with an unsupported type. */
 @AutoService(BugChecker.class)
 @BugPattern(
-    summary = "`@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` subtypes",
+    summary =
+        "By default, `@RequestParam` does not support `ImmutableCollection` and `ImmutableMap` subtypes",
     link = BUG_PATTERNS_BASE_URL + "RequestParamType",
     linkType = CUSTOM,
     severity = ERROR,
     tags = LIKELY_ERROR)
 public final class RequestParamType extends BugChecker implements VariableTreeMatcher {
   private static final long serialVersionUID = 1L;
-  private static final Matcher<VariableTree> HAS_UNSUPPORTED_REQUEST_PARAM =
-      allOf(
-          annotations(AT_LEAST_ONE, isType("org.springframework.web.bind.annotation.RequestParam")),
-          anyOf(isSubtypeOf(ImmutableCollection.class), isSubtypeOf(ImmutableMap.class)));
+  private static final String SUPPORTED_CUSTOM_TYPES_FLAG = "RequestParamType:SupportedCustomTypes";
 
-  /** Instantiates a new {@link RequestParamType} instance. */
-  public RequestParamType() {}
+  private final Matcher<VariableTree> hasUnsupportedRequestParamType;
+
+  /** Instantiates a default {@link RequestParamType} instance. */
+  public RequestParamType() {
+    this(ErrorProneFlags.empty());
+  }
+
+  /**
+   * Instantiates a customized {@link RequestParamType} instance.
+   *
+   * @param flags Any provided command line flags.
+   */
+  public RequestParamType(ErrorProneFlags flags) {
+    hasUnsupportedRequestParamType = hasUnsupportedRequestParamType(flags);
+  }
 
   @Override
   public Description matchVariable(VariableTree tree, VisitorState state) {
-    return HAS_UNSUPPORTED_REQUEST_PARAM.matches(tree, state)
+    return hasUnsupportedRequestParamType.matches(tree, state)
         ? describeMatch(tree)
         : Description.NO_MATCH;
   }
+
+  private static Matcher<VariableTree> hasUnsupportedRequestParamType(ErrorProneFlags flags) {
+    return allOf(
+        annotations(AT_LEAST_ONE, isType("org.springframework.web.bind.annotation.RequestParam")),
+        anyOf(isSubtypeOf(ImmutableCollection.class), isSubtypeOf(ImmutableMap.class)),
+        not(isSubtypeOfAny(Flags.getList(flags, SUPPORTED_CUSTOM_TYPES_FLAG))));
+  }
+
+  private static Matcher<Tree> isSubtypeOfAny(ImmutableList<String> inclusions) {
+    return anyOf(
+        inclusions.stream()
+            .map(inclusion -> isSubtypeOf(Suppliers.typeFromString(inclusion)))
+            .collect(toImmutableList()));
+  }
 }

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/ConflictDetection.java

@@ -0,0 +1,75 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import static tech.picnic.errorprone.bugpatterns.util.JavaKeywords.isValidIdentifier;
+
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ImportTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import com.sun.tools.javac.code.Type;
+import java.util.Optional;
+
+/** A set of helper methods for detecting conflicts that would be caused when applying fixes. */
+public final class ConflictDetection {
+  private ConflictDetection() {}
+
+  /**
+   * If applicable, returns a human-readable argument against assigning the given name to an
+   * existing method.
+   *
+   * <p>This method implements imperfect heuristics. Things it currently does not consider include
+   * the following:
+   *
+   * <ul>
+   *   <li>Whether the rename would merely introduce a method overload, rather than clashing with an
+   *       existing method declaration in its class or a supertype.
+   *   <li>Whether the rename would in fact clash with a static import. (It could be that a static
+   *       import of the same name is only referenced from lexical scopes in which the method under
+   *       consideration cannot be referenced directly.)
+   * </ul>
+   *
+   * @param method The method considered for renaming.
+   * @param newName The newly proposed name for the method.
+   * @param state The {@link VisitorState} to use when searching for blockers.
+   * @return A human-readable argument against assigning the proposed name to the given method, or
+   *     {@link Optional#empty()} if no blocker was found.
+   */
+  public static Optional<String> findMethodRenameBlocker(
+      MethodSymbol method, String newName, VisitorState state) {
+    if (isExistingMethodName(method.owner.type, newName, state)) {
+      return Optional.of(
+          String.format(
+              "a method named `%s` is already defined in this class or a supertype", newName));
+    }
+
+    if (isSimpleNameStaticallyImported(newName, state)) {
+      return Optional.of(String.format("`%s` is already statically imported", newName));
+    }
+
+    if (!isValidIdentifier(newName)) {
+      return Optional.of(String.format("`%s` is not a valid identifier", newName));
+    }
+
+    return Optional.empty();
+  }
+
+  private static boolean isExistingMethodName(Type clazz, String name, VisitorState state) {
+    return ASTHelpers.matchingMethods(state.getName(name), method -> true, clazz, state.getTypes())
+        .findAny()
+        .isPresent();
+  }
+
+  private static boolean isSimpleNameStaticallyImported(String simpleName, VisitorState state) {
+    return state.getPath().getCompilationUnit().getImports().stream()
+        .filter(ImportTree::isStatic)
+        .map(ImportTree::getQualifiedIdentifier)
+        .map(tree -> getStaticImportSimpleName(tree, state))
+        .anyMatch(simpleName::contentEquals);
+  }
+
+  private static CharSequence getStaticImportSimpleName(Tree tree, VisitorState state) {
+    String source = SourceCode.treeToString(tree, state);
+    return source.subSequence(source.lastIndexOf('.') + 1, source.length());
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/util/Flags.java

@@ -0,0 +1,25 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.ErrorProneFlags;
+
+/** Helper methods for working with {@link ErrorProneFlags}. */
+public final class Flags {
+  private Flags() {}
+
+  /**
+   * Returns the list of (comma-separated) arguments passed using the given Error Prone flag.
+   *
+   * @param errorProneFlags The full set of flags provided.
+   * @param name The name of the flag of interest.
+   * @return A non-{@code null} list of provided arguments; this list is empty if the flag was not
+   *     provided, or if the flag's value is the empty string.
+   */
+  public static ImmutableList<String> getList(ErrorProneFlags errorProneFlags, String name) {
+    return errorProneFlags
+        .getList(name)
+        .map(ImmutableList::copyOf)
+        .filter(flags -> !flags.equals(ImmutableList.of("")))
+        .orElseGet(ImmutableList::of);
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/AssertJOptionalRules.java

@@ -22,7 +22,6 @@ final class AssertJOptionalRules {
 
   static final class AssertThatOptional<T> {
     @BeforeTemplate
-    @SuppressWarnings("NullAway")
     ObjectAssert<T> before(Optional<T> optional) {
       return assertThat(optional.orElseThrow());
     }

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/JUnitToAssertJRules.java

@@ -0,0 +1,521 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.fail;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrowsExactly;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.errorprone.annotations.DoNotCall;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.google.errorprone.refaster.annotation.UseImportPolicy;
+import java.util.function.Supplier;
+import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.function.Executable;
+import org.junit.jupiter.api.function.ThrowingSupplier;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+/**
+ * Refaster rules to replace JUnit assertions with AssertJ equivalents.
+ *
+ * <p>Note that, while both libraries throw an {@link AssertionError} in case of an assertion
+ * failure, the exact subtype used generally differs.
+ */
+// XXX: Not all `org.assertj.core.api.Assertions` methods have an associated Refaster rule yet;
+// expand this class.
+// XXX: Introduce a `@Matcher` on `Executable` and `ThrowingSupplier` expressions, such that they
+// are only matched if they are also compatible with the `ThrowingCallable` functional interface.
+// When implementing such a matcher, note that expressions with a non-void return type such as
+// `() -> toString()` match both `ThrowingSupplier` and `ThrowingCallable`, but `() -> "constant"`
+// is only compatible with the former.
+@OnlineDocumentation
+final class JUnitToAssertJRules {
+  private JUnitToAssertJRules() {}
+
+  public ImmutableSet<?> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(
+        Assertions.class,
+        assertDoesNotThrow(() -> null),
+        assertInstanceOf(null, null),
+        assertThrows(null, null),
+        assertThrowsExactly(null, null),
+        (Runnable) () -> assertFalse(true),
+        (Runnable) () -> assertNotNull(null),
+        (Runnable) () -> assertNotSame(null, null),
+        (Runnable) () -> assertNull(null),
+        (Runnable) () -> assertSame(null, null),
+        (Runnable) () -> assertTrue(true));
+  }
+
+  static final class ThrowNewAssertionError {
+    @BeforeTemplate
+    void before() {
+      Assertions.fail();
+    }
+
+    @AfterTemplate
+    @DoNotCall
+    void after() {
+      throw new AssertionError();
+    }
+  }
+
+  static final class FailWithMessage<T> {
+    @BeforeTemplate
+    T before(String message) {
+      return Assertions.fail(message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    T after(String message) {
+      return fail(message);
+    }
+  }
+
+  static final class FailWithMessageAndThrowable<T> {
+    @BeforeTemplate
+    T before(String message, Throwable throwable) {
+      return Assertions.fail(message, throwable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    T after(String message, Throwable throwable) {
+      return fail(message, throwable);
+    }
+  }
+
+  static final class FailWithThrowable {
+    @BeforeTemplate
+    void before(Throwable throwable) {
+      Assertions.fail(throwable);
+    }
+
+    @AfterTemplate
+    @DoNotCall
+    void after(Throwable throwable) {
+      throw new AssertionError(throwable);
+    }
+  }
+
+  static final class AssertThatIsTrue {
+    @BeforeTemplate
+    void before(boolean actual) {
+      assertTrue(actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual) {
+      assertThat(actual).isTrue();
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsTrue {
+    @BeforeTemplate
+    void before(boolean actual, String message) {
+      assertTrue(actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual, String message) {
+      assertThat(actual).withFailMessage(message).isTrue();
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsTrue {
+    @BeforeTemplate
+    void before(boolean actual, Supplier<String> supplier) {
+      assertTrue(actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isTrue();
+    }
+  }
+
+  static final class AssertThatIsFalse {
+    @BeforeTemplate
+    void before(boolean actual) {
+      assertFalse(actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual) {
+      assertThat(actual).isFalse();
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsFalse {
+    @BeforeTemplate
+    void before(boolean actual, String message) {
+      assertFalse(actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual, String message) {
+      assertThat(actual).withFailMessage(message).isFalse();
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsFalse {
+    @BeforeTemplate
+    void before(boolean actual, Supplier<String> supplier) {
+      assertFalse(actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(boolean actual, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isFalse();
+    }
+  }
+
+  static final class AssertThatIsNull {
+    @BeforeTemplate
+    void before(Object actual) {
+      assertNull(actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual) {
+      assertThat(actual).isNull();
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsNull {
+    @BeforeTemplate
+    void before(Object actual, String message) {
+      assertNull(actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, String message) {
+      assertThat(actual).withFailMessage(message).isNull();
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsNull {
+    @BeforeTemplate
+    void before(Object actual, Supplier<String> supplier) {
+      assertNull(actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isNull();
+    }
+  }
+
+  static final class AssertThatIsNotNull {
+    @BeforeTemplate
+    void before(Object actual) {
+      assertNotNull(actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual) {
+      assertThat(actual).isNotNull();
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsNotNull {
+    @BeforeTemplate
+    void before(Object actual, String message) {
+      assertNotNull(actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, String message) {
+      assertThat(actual).withFailMessage(message).isNotNull();
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsNotNull {
+    @BeforeTemplate
+    void before(Object actual, Supplier<String> supplier) {
+      assertNotNull(actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isNotNull();
+    }
+  }
+
+  static final class AssertThatIsSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected) {
+      assertSame(expected, actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected) {
+      assertThat(actual).isSameAs(expected);
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected, String message) {
+      assertSame(expected, actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected, String message) {
+      assertThat(actual).withFailMessage(message).isSameAs(expected);
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected, Supplier<String> supplier) {
+      assertSame(expected, actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isSameAs(expected);
+    }
+  }
+
+  static final class AssertThatIsNotSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected) {
+      assertNotSame(expected, actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected) {
+      assertThat(actual).isNotSameAs(expected);
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsNotSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected, String message) {
+      assertNotSame(expected, actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected, String message) {
+      assertThat(actual).withFailMessage(message).isNotSameAs(expected);
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsNotSameAs {
+    @BeforeTemplate
+    void before(Object actual, Object expected, Supplier<String> supplier) {
+      assertNotSame(expected, actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Object expected, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isNotSameAs(expected);
+    }
+  }
+
+  static final class AssertThatThrownByIsExactlyInstanceOf<T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz) {
+      assertThrowsExactly(clazz, throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz) {
+      assertThatThrownBy(throwingCallable).isExactlyInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatThrownByWithFailMessageStringIsExactlyInstanceOf<
+      T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz, String message) {
+      assertThrowsExactly(clazz, throwingCallable, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz, String message) {
+      assertThatThrownBy(throwingCallable).withFailMessage(message).isExactlyInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatThrownByWithFailMessageSupplierIsExactlyInstanceOf<
+      T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+      assertThrowsExactly(clazz, throwingCallable, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+      assertThatThrownBy(throwingCallable).withFailMessage(supplier).isExactlyInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatThrownByIsInstanceOf<T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz) {
+      assertThrows(clazz, throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz) {
+      assertThatThrownBy(throwingCallable).isInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatThrownByWithFailMessageStringIsInstanceOf<T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz, String message) {
+      assertThrows(clazz, throwingCallable, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz, String message) {
+      assertThatThrownBy(throwingCallable).withFailMessage(message).isInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatThrownByWithFailMessageSupplierIsInstanceOf<T extends Throwable> {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+      assertThrows(clazz, throwingCallable, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Class<T> clazz, Supplier<String> supplier) {
+      assertThatThrownBy(throwingCallable).withFailMessage(supplier).isInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatCodeDoesNotThrowAnyException {
+    @BeforeTemplate
+    void before(Executable throwingCallable) {
+      assertDoesNotThrow(throwingCallable);
+    }
+
+    @BeforeTemplate
+    void before(ThrowingSupplier<?> throwingCallable) {
+      assertDoesNotThrow(throwingCallable);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable) {
+      assertThatCode(throwingCallable).doesNotThrowAnyException();
+    }
+  }
+
+  static final class AssertThatCodeWithFailMessageStringDoesNotThrowAnyException {
+    @BeforeTemplate
+    void before(Executable throwingCallable, String message) {
+      assertDoesNotThrow(throwingCallable, message);
+    }
+
+    @BeforeTemplate
+    void before(ThrowingSupplier<?> throwingCallable, String message) {
+      assertDoesNotThrow(throwingCallable, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, String message) {
+      assertThatCode(throwingCallable).withFailMessage(message).doesNotThrowAnyException();
+    }
+  }
+
+  static final class AssertThatCodeWithFailMessageSupplierDoesNotThrowAnyException {
+    @BeforeTemplate
+    void before(Executable throwingCallable, Supplier<String> supplier) {
+      assertDoesNotThrow(throwingCallable, supplier);
+    }
+
+    @BeforeTemplate
+    void before(ThrowingSupplier<?> throwingCallable, Supplier<String> supplier) {
+      assertDoesNotThrow(throwingCallable, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(ThrowingCallable throwingCallable, Supplier<String> supplier) {
+      assertThatCode(throwingCallable).withFailMessage(supplier).doesNotThrowAnyException();
+    }
+  }
+
+  static final class AssertThatIsInstanceOf<T> {
+    @BeforeTemplate
+    void before(Object actual, Class<T> clazz) {
+      assertInstanceOf(clazz, actual);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Class<T> clazz) {
+      assertThat(actual).isInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatWithFailMessageStringIsInstanceOf<T> {
+    @BeforeTemplate
+    void before(Object actual, Class<T> clazz, String message) {
+      assertInstanceOf(clazz, actual, message);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Class<T> clazz, String message) {
+      assertThat(actual).withFailMessage(message).isInstanceOf(clazz);
+    }
+  }
+
+  static final class AssertThatWithFailMessageSupplierIsInstanceOf<T> {
+    @BeforeTemplate
+    void before(Object actual, Class<T> clazz, Supplier<String> supplier) {
+      assertInstanceOf(clazz, actual, supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    void after(Object actual, Class<T> clazz, Supplier<String> supplier) {
+      assertThat(actual).withFailMessage(supplier).isInstanceOf(clazz);
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/JooqRules.java

@@ -0,0 +1,29 @@
+package tech.picnic.errorprone.refasterrules;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.stream.Stream;
+import org.jooq.Record;
+import org.jooq.ResultQuery;
+import tech.picnic.errorprone.refaster.annotation.Description;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
+
+@OnlineDocumentation
+final class JooqRules {
+  private JooqRules() {}
+
+  /** Prefer eagerly fetching data over (lazy) streaming to avoid potentially leaking resources. */
+  @Description(
+      "Prefer eagerly fetching data over (lazy) streaming to avoid potentially leaking resources.")
+  static final class ResultQueryFetchStream {
+    @BeforeTemplate
+    Stream<?> before(ResultQuery<? extends Record> resultQuery) {
+      return resultQuery.stream();
+    }
+
+    @AfterTemplate
+    Stream<?> after(ResultQuery<? extends Record> resultQuery) {
+      return resultQuery.fetch().stream();
+    }
+  }
+}

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/MapRules.java

@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
@@ -43,6 +45,21 @@ final class MapRules {
     }
   }
 
+  /** Prefer {@link Map#getOrDefault(Object, Object)} over more contrived alternatives. */
+  // XXX: Note that `requireNonNullElse` throws an NPE if the second argument is `null`, while the
+  // alternative does not.
+  static final class MapGetOrDefault<K, V, T> {
+    @BeforeTemplate
+    V before(Map<K, V> map, T key, V defaultValue) {
+      return requireNonNullElse(map.get(key), defaultValue);
+    }
+
+    @AfterTemplate
+    V after(Map<K, V> map, T key, V defaultValue) {
+      return map.getOrDefault(key, defaultValue);
+    }
+  }
+
   /** Prefer {@link Map#isEmpty()} over more contrived alternatives. */
   static final class MapIsEmpty<K, V> {
     @BeforeTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/NullRules.java

@@ -2,13 +2,17 @@ package tech.picnic.errorprone.refasterrules;
 
 import static com.google.errorprone.refaster.ImportPolicy.STATIC_IMPORT_ALWAYS;
 import static java.util.Objects.requireNonNullElse;
+import static java.util.Objects.requireNonNullElseGet;
 
 import com.google.common.base.MoreObjects;
+import com.google.errorprone.refaster.Refaster;
 import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
@@ -43,13 +47,18 @@ final class NullRules {
     }
   }
 
-  /** Prefer {@link Objects#requireNonNullElse(Object, Object)} over the Guava alternative. */
-  // XXX: This rule is not valid in case `second` is `@Nullable`: in that case the Guava variant
-  // will return `null`, while the JDK variant will throw an NPE.
+  /**
+   * Prefer {@link Objects#requireNonNullElse(Object, Object)} over non-JDK or more contrived
+   * alternatives.
+   */
+  // XXX: This rule is not valid in case `second` is `@Nullable`: in that case the Guava and
+  // `Optional` variants will return `null`, where the `requireNonNullElse` alternative will throw
+  // an NPE.
   static final class RequireNonNullElse<T> {
     @BeforeTemplate
     T before(T first, T second) {
-      return MoreObjects.firstNonNull(first, second);
+      return Refaster.anyOf(
+          MoreObjects.firstNonNull(first, second), Optional.ofNullable(first).orElse(second));
     }
 
     @AfterTemplate
@@ -59,6 +68,26 @@ final class NullRules {
     }
   }
 
+  /**
+   * Prefer {@link Objects#requireNonNullElseGet(Object, Supplier)} over more contrived
+   * alternatives.
+   */
+  // XXX: This rule is not valid in case `supplier` yields `@Nullable` values: in that case the
+  // `Optional` variant will return `null`, where the `requireNonNullElseGet` alternative will throw
+  // an NPE.
+  static final class RequireNonNullElseGet<T, S extends T> {
+    @BeforeTemplate
+    T before(T object, Supplier<S> supplier) {
+      return Optional.ofNullable(object).orElseGet(supplier);
+    }
+
+    @AfterTemplate
+    @UseImportPolicy(STATIC_IMPORT_ALWAYS)
+    T after(T object, Supplier<S> supplier) {
+      return requireNonNullElseGet(object, supplier);
+    }
+  }
+
   /** Prefer {@link Objects#isNull(Object)} over the equivalent lambda function. */
   static final class IsNullFunction<T> {
     @BeforeTemplate

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java

@@ -369,13 +369,11 @@ final class ReactorRules {
   static final class MonoIdentity<T> {
     @BeforeTemplate
     Mono<T> before(Mono<T> mono) {
-      return mono.switchIfEmpty(Mono.empty());
+      return Refaster.anyOf(
+          mono.switchIfEmpty(Mono.empty()), mono.flux().next(), mono.flux().singleOrEmpty());
     }
 
-    // XXX: Review the suppression once NullAway has better support for generics. Keep an eye on
-    // https://github.com/uber/NullAway/issues?q=is%3Aopen+generics.
     @BeforeTemplate
-    @SuppressWarnings("NullAway" /* False positive. */)
     Mono<@Nullable Void> before2(Mono<@Nullable Void> mono) {
       return mono.then();
     }
@@ -476,6 +474,11 @@ final class ReactorRules {
    * Flux}.
    */
   abstract static class MonoFlatMapToFlux<T, S> {
+    // XXX: It would be more expressive if this `@Placeholder` were replaced with a `Function<?
+    // super T, ? extends Mono<? extends S>>` parameter, so that compatible non-lambda expression
+    // arguments to `flatMapMany` are also matched. However, the type inferred for lambda and method
+    // reference expressions passed to `flatMapMany` appears to always be `Function<T, Publisher<?
+    // extends S>>`, which doesn't match. Find a solution.
     @Placeholder(allowsIdentity = true)
     abstract Mono<S> transformation(@MayOptionallyUse T value);
 

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/TestNGToAssertJRules.java

@@ -28,6 +28,7 @@ import java.util.Set;
 import org.assertj.core.api.ThrowableAssert.ThrowingCallable;
 import org.testng.Assert;
 import org.testng.Assert.ThrowingRunnable;
+import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /**
  * Refaster rules that replace TestNG assertions with equivalent AssertJ assertions.
@@ -72,6 +73,7 @@ import org.testng.Assert.ThrowingRunnable;
 // XXX: As-is these rules do not result in a complete migration:
 // - Expressions containing comments are skipped due to a limitation of Refaster.
 // - Assertions inside lambda expressions are also skipped. Unclear why.
+@OnlineDocumentation
 final class TestNGToAssertJRules {
   private TestNGToAssertJRules() {}
 

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AmbiguousJsonCreatorTest.java

@@ -3,21 +3,16 @@ package tech.picnic.errorprone.bugpatterns;
 import static com.google.common.base.Predicates.containsPattern;
 
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class AmbiguousJsonCreatorTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(AmbiguousJsonCreator.class, getClass())
-          .expectErrorMessage(
-              "X",
-              containsPattern("`JsonCreator.Mode` should be set for single-argument creators"));
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(AmbiguousJsonCreator.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(AmbiguousJsonCreator.class, getClass())
+        .expectErrorMessage(
+            "X", containsPattern("`JsonCreator.Mode` should be set for single-argument creators"))
         .addSourceLines(
             "Container.java",
             "import com.fasterxml.jackson.annotation.JsonCreator;",
@@ -118,7 +113,7 @@ final class AmbiguousJsonCreatorTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(AmbiguousJsonCreator.class, getClass())
         .addInputLines(
             "A.java",
             "import com.fasterxml.jackson.annotation.JsonCreator;",
@@ -143,6 +138,6 @@ final class AmbiguousJsonCreatorTest {
             "    return FOO;",
             "  }",
             "}")
-        .doTest(BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH);
+        .doTest(TestMode.TEXT_MATCH);
   }
 }

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AssertJIsNullTest.java

@@ -7,14 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class AssertJIsNullTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(AssertJIsNull.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(AssertJIsNull.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(AssertJIsNull.class, getClass())
         .addSourceLines(
             "A.java",
             "import static org.assertj.core.api.Assertions.assertThat;",
@@ -38,7 +33,7 @@ final class AssertJIsNullTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(AssertJIsNull.class, getClass())
         .addInputLines(
             "A.java",
             "import static org.assertj.core.api.Assertions.assertThat;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/AutowiredConstructorTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class AutowiredConstructorTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(AutowiredConstructor.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(AutowiredConstructor.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(AutowiredConstructor.class, getClass())
         .addSourceLines(
             "Container.java",
             "import com.google.errorprone.annotations.Immutable;",
@@ -71,7 +66,7 @@ final class AutowiredConstructorTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(AutowiredConstructor.class, getClass())
         .addInputLines(
             "Container.java",
             "import org.springframework.beans.factory.annotation.Autowired;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CanonicalAnnotationSyntaxTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class CanonicalAnnotationSyntaxTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass())
         .addSourceLines(
             "pkg/A.java",
             "package pkg;",
@@ -133,7 +128,7 @@ final class CanonicalAnnotationSyntaxTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(CanonicalAnnotationSyntax.class, getClass())
         .addInputLines(
             "pkg/A.java",
             "package pkg;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/CollectorMutabilityTest.java

@@ -8,14 +8,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class CollectorMutabilityTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(CollectorMutability.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(CollectorMutability.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(CollectorMutability.class, getClass())
         .addSourceLines(
             "A.java",
             "import static com.google.common.collect.ImmutableList.toImmutableList;",
@@ -67,7 +62,7 @@ final class CollectorMutabilityTest {
 
   @Test
   void identificationWithoutGuavaOnClasspath() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(CollectorMutability.class, getClass())
         .withClasspath()
         .addSourceLines(
             "A.java",
@@ -84,7 +79,7 @@ final class CollectorMutabilityTest {
 
   @Test
   void replacementFirstSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(CollectorMutability.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.util.stream.Collectors.toList;",
@@ -141,7 +136,7 @@ final class CollectorMutabilityTest {
 
   @Test
   void replacementSecondSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(CollectorMutability.class, getClass())
         .setFixChooser(SECOND)
         .addInputLines(
             "A.java",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/EmptyMethodTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class EmptyMethodTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(EmptyMethod.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(EmptyMethod.class, getClass())
         .addSourceLines(
             "A.java",
             "class A {",
@@ -69,7 +64,7 @@ final class EmptyMethodTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(EmptyMethod.class, getClass())
         .addInputLines(
             "A.java",
             "final class A {",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ErrorProneTestHelperSourceFormatTest.java

@@ -6,15 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class ErrorProneTestHelperSourceFormatTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(ErrorProneTestHelperSourceFormat.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(
-          ErrorProneTestHelperSourceFormat.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(ErrorProneTestHelperSourceFormat.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.errorprone.BugCheckerRefactoringTestHelper;",
@@ -63,7 +57,7 @@ final class ErrorProneTestHelperSourceFormatTest {
      * Verifies that import sorting and code formatting is performed unconditionally, while unused
      * imports are removed unless part of a `BugCheckerRefactoringTestHelper` expected output file.
      */
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(ErrorProneTestHelperSourceFormat.class, getClass())
         .addInputLines(
             "A.java",
             "import com.google.errorprone.BugCheckerRefactoringTestHelper;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java

@@ -4,12 +4,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class ExplicitEnumOrderingTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(ExplicitEnumOrdering.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(ExplicitEnumOrdering.class, getClass())
         .addSourceLines(
             "A.java",
             "import static java.lang.annotation.RetentionPolicy.CLASS;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FluxFlatMapUsageTest.java

@@ -1,7 +1,5 @@
 package tech.picnic.errorprone.bugpatterns;
 
-import static com.google.errorprone.BugCheckerRefactoringTestHelper.newInstance;
-
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
@@ -9,14 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class FluxFlatMapUsageTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(FluxFlatMapUsage.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      newInstance(FluxFlatMapUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(FluxFlatMapUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.function.BiFunction;",
@@ -73,7 +66,7 @@ final class FluxFlatMapUsageTest {
 
   @Test
   void replacementFirstSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(FluxFlatMapUsage.class, getClass())
         .setFixChooser(FixChoosers.FIRST)
         .addInputLines(
             "A.java",
@@ -108,7 +101,7 @@ final class FluxFlatMapUsageTest {
 
   @Test
   void replacementSecondSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(FluxFlatMapUsage.class, getClass())
         .setFixChooser(FixChoosers.SECOND)
         .addInputLines(
             "A.java",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/FormatStringConcatenationTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class FormatStringConcatenationTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(FormatStringConcatenation.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(FormatStringConcatenation.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(FormatStringConcatenation.class, getClass())
         .addSourceLines(
             "A.java",
             "import static com.google.common.base.Preconditions.checkArgument;",
@@ -309,7 +304,7 @@ final class FormatStringConcatenationTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(FormatStringConcatenation.class, getClass())
         .addInputLines(
             "A.java",
             "import static com.google.common.base.Preconditions.checkArgument;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/IdentityConversionTest.java

@@ -7,14 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class IdentityConversionTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(IdentityConversion.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(IdentityConversion.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(IdentityConversion.class, getClass())
         .addSourceLines(
             "A.java",
             "import static com.google.errorprone.matchers.Matchers.instanceMethod;",
@@ -184,7 +179,7 @@ final class IdentityConversionTest {
 
   @Test
   void replacementFirstSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(IdentityConversion.class, getClass())
         .setFixChooser(FixChoosers.FIRST)
         .addInputLines(
             "A.java",
@@ -291,7 +286,7 @@ final class IdentityConversionTest {
 
   @Test
   void replacementSecondSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(IdentityConversion.class, getClass())
         .setFixChooser(FixChoosers.SECOND)
         .addInputLines(
             "A.java",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ImmutablesSortedSetComparatorTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class ImmutablesSortedSetComparatorTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(ImmutablesSortedSetComparator.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(ImmutablesSortedSetComparator.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(ImmutablesSortedSetComparator.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.common.collect.ContiguousSet;",
@@ -109,7 +104,7 @@ final class ImmutablesSortedSetComparatorTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(ImmutablesSortedSetComparator.class, getClass())
         .addInputLines(
             "A.java",
             "import com.google.common.collect.ImmutableSortedSet;",
@@ -147,7 +142,7 @@ final class ImmutablesSortedSetComparatorTest {
 
   @Test
   void replacementWithImportClash() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(ImmutablesSortedSetComparator.class, getClass())
         .addInputLines(
             "MySpringService.java",
             "import com.google.common.collect.ImmutableSortedSet;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/IsInstanceLambdaUsageTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class IsInstanceLambdaUsageTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(IsInstanceLambdaUsage.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(IsInstanceLambdaUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(IsInstanceLambdaUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.stream.Stream;",
@@ -46,7 +41,7 @@ final class IsInstanceLambdaUsageTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(IsInstanceLambdaUsage.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.stream.Stream;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitClassModifiersTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class JUnitClassModifiersTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(JUnitClassModifiers.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(JUnitClassModifiers.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(JUnitClassModifiers.class, getClass())
         .addSourceLines(
             "Container.java",
             "import org.junit.jupiter.api.Test;",
@@ -98,7 +93,7 @@ final class JUnitClassModifiersTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(JUnitClassModifiers.class, getClass())
         .addInputLines(
             "A.java",
             "import org.junit.jupiter.api.Test;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitMethodDeclarationTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class JUnitMethodDeclarationTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(JUnitMethodDeclaration.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(JUnitMethodDeclaration.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(JUnitMethodDeclaration.class, getClass())
         .addSourceLines(
             "A.java",
             "import static org.junit.jupiter.params.provider.Arguments.arguments;",
@@ -345,7 +340,7 @@ final class JUnitMethodDeclarationTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(JUnitMethodDeclaration.class, getClass())
         .addInputLines(
             "A.java",
             "import static org.junit.jupiter.params.provider.Arguments.arguments;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationAttributeListingTest.java

@@ -7,22 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class LexicographicalAnnotationAttributeListingTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(
-          LexicographicalAnnotationAttributeListing.class, getClass());
-  private final CompilationTestHelper restrictedCompilationTestHelper =
-      CompilationTestHelper.newInstance(LexicographicalAnnotationAttributeListing.class, getClass())
-          .setArgs(
-              ImmutableList.of(
-                  "-XepOpt:LexicographicalAnnotationAttributeListing:Includes=pkg.A.Foo,pkg.A.Bar",
-                  "-XepOpt:LexicographicalAnnotationAttributeListing:Excludes=pkg.A.Bar#value"));
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(
-          LexicographicalAnnotationAttributeListing.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(LexicographicalAnnotationAttributeListing.class, getClass())
         .addSourceLines(
             "A.java",
             "import static java.math.RoundingMode.DOWN;",
@@ -165,7 +152,8 @@ final class LexicographicalAnnotationAttributeListingTest {
   // `CanonicalAnnotationSyntax` checker correct the situation in a subsequent run.
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(
+            LexicographicalAnnotationAttributeListing.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.math.RoundingMode.DOWN;",
@@ -246,7 +234,11 @@ final class LexicographicalAnnotationAttributeListingTest {
   @Test
   void filtering() {
     /* Some violations are not flagged because they are not in- or excluded. */
-    restrictedCompilationTestHelper
+    CompilationTestHelper.newInstance(LexicographicalAnnotationAttributeListing.class, getClass())
+        .setArgs(
+            ImmutableList.of(
+                "-XepOpt:LexicographicalAnnotationAttributeListing:Includes=pkg.A.Foo,pkg.A.Bar",
+                "-XepOpt:LexicographicalAnnotationAttributeListing:Excludes=pkg.A.Bar#value"))
         .addSourceLines(
             "pkg/A.java",
             "package pkg;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/LexicographicalAnnotationListingTest.java

@@ -6,15 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class LexicographicalAnnotationListingTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(LexicographicalAnnotationListing.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(
-          LexicographicalAnnotationListing.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(LexicographicalAnnotationListing.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.lang.annotation.ElementType;",
@@ -133,7 +127,7 @@ final class LexicographicalAnnotationListingTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(LexicographicalAnnotationListing.class, getClass())
         .addInputLines(
             "A.java",
             "import java.lang.annotation.ElementType;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MethodReferenceUsageTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class MethodReferenceUsageTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(MethodReferenceUsage.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(MethodReferenceUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(MethodReferenceUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.common.collect.Streams;",
@@ -323,7 +318,7 @@ final class MethodReferenceUsageTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(MethodReferenceUsage.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.util.Collections.emptyList;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MissingRefasterAnnotationTest.java

@@ -6,16 +6,12 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class MissingRefasterAnnotationTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(MissingRefasterAnnotation.class, getClass())
-          .expectErrorMessage(
-              "X",
-              containsPattern(
-                  "The Refaster rule contains a method without any Refaster annotations"));
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(MissingRefasterAnnotation.class, getClass())
+        .expectErrorMessage(
+            "X",
+            containsPattern("The Refaster rule contains a method without any Refaster annotations"))
         .addSourceLines(
             "A.java",
             "import com.google.errorprone.refaster.annotation.AfterTemplate;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/MockitoStubbingTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class MockitoStubbingTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(MockitoStubbing.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(MockitoStubbing.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(MockitoStubbing.class, getClass())
         .addSourceLines(
             "A.java",
             "import static org.mockito.ArgumentMatchers.eq;",
@@ -55,7 +50,7 @@ final class MockitoStubbingTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(MockitoStubbing.class, getClass())
         .addInputLines(
             "A.java",
             "import static org.mockito.ArgumentMatchers.eq;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NestedOptionalsTest.java

@@ -4,12 +4,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class NestedOptionalsTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(NestedOptionals.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(NestedOptionals.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Optional;",
@@ -42,7 +39,7 @@ final class NestedOptionalsTest {
 
   @Test
   void identificationOptionalTypeNotLoaded() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(NestedOptionals.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.time.Duration;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonEmptyMonoTest.java

@@ -7,14 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class NonEmptyMonoTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(NonEmptyMono.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(NonEmptyMono.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(NonEmptyMono.class, getClass())
         .addSourceLines(
             "A.java",
             "import static com.google.common.collect.ImmutableList.toImmutableList;",
@@ -111,7 +106,7 @@ final class NonEmptyMonoTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(NonEmptyMono.class, getClass())
         .addInputLines(
             "A.java",
             "import static com.google.common.collect.ImmutableList.toImmutableList;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/PrimitiveComparisonTest.java

@@ -5,22 +5,21 @@ import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
+// XXX: There are no tests for multiple replacements within the same expression:
+// - Error Prone doesn't currently support this, it seems.
+// - The `BugCheckerRefactoringTestHelper` throws an exception in this case.
+// - During actual compilation only the first replacement is applied.
+// XXX: Can we perhaps work-around this by describing the fixes in reverse order?
 final class PrimitiveComparisonTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass());
-
-  // XXX: There are no tests for multiple replacements within the same expression:
-  // - Error Prone doesn't currently support this, it seems.
-  // - The `BugCheckerRefactoringTestHelper` throws an exception in this case.
-  // - During actual compilation only the first replacement is applied.
-  // XXX: Can we perhaps work-around this by describing the fixes in reverse order?
-
-  // The logic for `char` and `short` is exactly analogous to the `byte` case.
+  /**
+   * Tests the identification of {@code byte} comparisons for which boxing can be avoided.
+   *
+   * @implNote The logic for {@code char} and {@code short} is exactly analogous to the {@code byte}
+   *     case.
+   */
   @Test
   void byteComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -120,7 +119,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void intComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -227,7 +226,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void longComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -318,7 +317,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void floatComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -386,7 +385,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void doubleComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -461,7 +460,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void stringComparison() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.util.Comparator;",
@@ -497,7 +496,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithPrimitiveVariants() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.Comparator;",
@@ -577,7 +576,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithBoxedVariants() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.Comparator;",
@@ -643,7 +642,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithPrimitiveVariantsUsingStaticImports() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.util.Comparator.comparing;",
@@ -682,7 +681,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithBoxedVariantsUsingStaticImports() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.util.Comparator.comparingDouble;",
@@ -723,7 +722,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithPrimitiveVariantsInComplexSyntacticalContext() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.Comparator;",
@@ -755,7 +754,7 @@ final class PrimitiveComparisonTest {
 
   @Test
   void replacementWithBoxedVariantsInComplexSyntacticalContext() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(PrimitiveComparison.class, getClass())
         .addInputLines(
             "A.java",
             "import java.util.Comparator;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RedundantStringConversionTest.java

@@ -12,13 +12,6 @@ import org.junit.jupiter.api.Test;
 final class RedundantStringConversionTest {
   private final CompilationTestHelper compilationTestHelper =
       CompilationTestHelper.newInstance(RedundantStringConversion.class, getClass());
-  private final CompilationTestHelper customizedCompilationTestHelper =
-      CompilationTestHelper.newInstance(RedundantStringConversion.class, getClass())
-          .setArgs(
-              ImmutableList.of(
-                  "-XepOpt:RedundantStringConversion:ExtraConversionMethods=java.lang.Enum#name(),A#name(),A.B#toString(int)"));
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(RedundantStringConversion.class, getClass());
 
   @Test
   void identificationOfIdentityTransformation() {
@@ -416,7 +409,10 @@ final class RedundantStringConversionTest {
 
   @Test
   void identificationOfCustomConversionMethod() {
-    customizedCompilationTestHelper
+    CompilationTestHelper.newInstance(RedundantStringConversion.class, getClass())
+        .setArgs(
+            ImmutableList.of(
+                "-XepOpt:RedundantStringConversion:ExtraConversionMethods=java.lang.Enum#name(),A#name(),A.B#toString(int)"))
         .addSourceLines(
             "A.java",
             "import java.math.RoundingMode;",
@@ -509,7 +505,7 @@ final class RedundantStringConversionTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(RedundantStringConversion.class, getClass())
         .addInputLines(
             "A.java",
             "class A {",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterAnyOfUsageTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class RefasterAnyOfUsageTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(RefasterAnyOfUsage.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(RefasterAnyOfUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(RefasterAnyOfUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.errorprone.refaster.Refaster;",
@@ -38,7 +33,7 @@ final class RefasterAnyOfUsageTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(RefasterAnyOfUsage.class, getClass())
         .addInputLines(
             "A.java",
             "import com.google.errorprone.refaster.Refaster;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RefasterRuleModifiersTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class RefasterRuleModifiersTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(RefasterRuleModifiers.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(RefasterRuleModifiers.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(RefasterRuleModifiers.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.errorprone.refaster.annotation.BeforeTemplate;",
@@ -136,7 +131,7 @@ final class RefasterRuleModifiersTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(RefasterRuleModifiers.class, getClass())
         .addInputLines(
             "A.java",
             "import com.google.errorprone.refaster.annotation.BeforeTemplate;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RequestMappingAnnotationTest.java

@@ -4,12 +4,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class RequestMappingAnnotationTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(RequestMappingAnnotation.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(RequestMappingAnnotation.class, getClass())
         .addSourceLines(
             "A.java",
             "import java.io.InputStream;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/RequestParamTypeTest.java

@@ -4,12 +4,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class RequestParamTypeTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(RequestParamType.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(RequestParamType.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.google.common.collect.ImmutableBiMap;",
@@ -63,4 +60,55 @@ final class RequestParamTypeTest {
             "}")
         .doTest();
   }
+
+  @Test
+  void identificationRestricted() {
+    CompilationTestHelper.newInstance(RequestParamType.class, getClass())
+        .setArgs(
+            "-XepOpt:RequestParamType:SupportedCustomTypes=com.google.common.collect.ImmutableSet,com.google.common.collect.ImmutableSortedMultiset")
+        .addSourceLines(
+            "A.java",
+            "import com.google.common.collect.ImmutableBiMap;",
+            "import com.google.common.collect.ImmutableCollection;",
+            "import com.google.common.collect.ImmutableList;",
+            "import com.google.common.collect.ImmutableMap;",
+            "import com.google.common.collect.ImmutableMultiset;",
+            "import com.google.common.collect.ImmutableSet;",
+            "import com.google.common.collect.ImmutableSortedMultiset;",
+            "import com.google.common.collect.ImmutableSortedSet;",
+            "import org.springframework.web.bind.annotation.GetMapping;",
+            "import org.springframework.web.bind.annotation.RequestParam;",
+            "",
+            "interface A {",
+            "  @GetMapping",
+            "  // BUG: Diagnostic contains:",
+            "  A immutableCollection(@RequestParam ImmutableCollection<String> param);",
+            "",
+            "  @GetMapping",
+            "  // BUG: Diagnostic contains:",
+            "  A immutableList(@RequestParam ImmutableList<String> param);",
+            "",
+            "  @GetMapping",
+            "  A immutableSet(@RequestParam ImmutableSet<String> param);",
+            "",
+            "  @GetMapping",
+            "  A immutableSortedSet(@RequestParam ImmutableSortedSet<String> param);",
+            "",
+            "  @GetMapping",
+            "  // BUG: Diagnostic contains:",
+            "  A immutableMultiset(@RequestParam ImmutableMultiset<String> param);",
+            "",
+            "  @GetMapping",
+            "  A immutableSortedMultiset(@RequestParam ImmutableSortedMultiset<String> param);",
+            "",
+            "  @GetMapping",
+            "  // BUG: Diagnostic contains:",
+            "  A immutableMap(@RequestParam ImmutableMap<String, String> param);",
+            "",
+            "  @GetMapping",
+            "  // BUG: Diagnostic contains:",
+            "  A immutableBiMap(@RequestParam ImmutableBiMap<String, String> param);",
+            "}")
+        .doTest();
+  }
 }

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ScheduledTransactionTraceTest.java

@@ -7,14 +7,9 @@ import org.junit.jupiter.api.Test;
 import org.springframework.scheduling.annotation.Scheduled;
 
 final class ScheduledTransactionTraceTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(ScheduledTransactionTrace.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(ScheduledTransactionTrace.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(ScheduledTransactionTrace.class, getClass())
         .addSourceLines(
             "A.java",
             "import com.newrelic.api.agent.Trace;",
@@ -46,7 +41,7 @@ final class ScheduledTransactionTraceTest {
 
   @Test
   void identificationWithoutNewRelicAgentApiOnClasspath() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(ScheduledTransactionTrace.class, getClass())
         .withClasspath(Scheduled.class)
         .addSourceLines(
             "A.java",
@@ -61,7 +56,7 @@ final class ScheduledTransactionTraceTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(ScheduledTransactionTrace.class, getClass())
         .addInputLines(
             "A.java",
             "import com.newrelic.api.agent.Trace;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/Slf4jLogStatementTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class Slf4jLogStatementTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(Slf4jLogStatement.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(Slf4jLogStatement.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(Slf4jLogStatement.class, getClass())
         .addSourceLines(
             "A.java",
             "import org.slf4j.Logger;",
@@ -96,7 +91,7 @@ final class Slf4jLogStatementTest {
   // XXX: Drop what's unused.
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(Slf4jLogStatement.class, getClass())
         .addInputLines(
             "A.java",
             "import org.slf4j.Logger;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/SpringMvcAnnotationTest.java

@@ -6,14 +6,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class SpringMvcAnnotationTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(SpringMvcAnnotation.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(SpringMvcAnnotation.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(SpringMvcAnnotation.class, getClass())
         .addSourceLines(
             "A.java",
             "import static org.springframework.web.bind.annotation.RequestMethod.DELETE;",
@@ -85,7 +80,7 @@ final class SpringMvcAnnotationTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(SpringMvcAnnotation.class, getClass())
         .addInputLines(
             "A.java",
             "import static org.springframework.web.bind.annotation.RequestMethod.PATCH;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportTest.java

@@ -8,11 +8,6 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class StaticImportTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(StaticImport.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(StaticImport.class, getClass());
-
   @Test
   void candidateMethodsAreNotRedundant() {
     assertThat(StaticImport.STATIC_IMPORT_CANDIDATE_MEMBERS.keySet())
@@ -33,7 +28,7 @@ final class StaticImportTest {
 
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(StaticImport.class, getClass())
         .addSourceLines(
             "A.java",
             "import static com.google.common.collect.ImmutableMap.toImmutableMap;",
@@ -118,7 +113,7 @@ final class StaticImportTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(StaticImport.class, getClass())
         .addInputLines(
             "A.java",
             "import static java.util.function.Predicate.not;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StringCaseLocaleUsageTest.java

@@ -1,7 +1,5 @@
 package tech.picnic.errorprone.bugpatterns;
 
-import static com.google.errorprone.BugCheckerRefactoringTestHelper.newInstance;
-
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
@@ -9,14 +7,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class StringCaseLocaleUsageTest {
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(StringCaseLocaleUsage.class, getClass());
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      newInstance(StringCaseLocaleUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(StringCaseLocaleUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import static java.util.Locale.ROOT;",
@@ -54,7 +47,7 @@ final class StringCaseLocaleUsageTest {
 
   @Test
   void replacementFirstSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(StringCaseLocaleUsage.class, getClass())
         .setFixChooser(FixChoosers.FIRST)
         .addInputLines(
             "A.java",
@@ -93,7 +86,7 @@ final class StringCaseLocaleUsageTest {
 
   @Test
   void replacementSecondSuggestedFix() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(StringCaseLocaleUsage.class, getClass())
         .setFixChooser(FixChoosers.SECOND)
         .addInputLines(
             "A.java",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StringJoinTest.java

@@ -8,17 +8,12 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class StringJoinTest {
-  private final CompilationTestHelper compilationHelper =
-      CompilationTestHelper.newInstance(StringJoin.class, getClass())
-          .expectErrorMessage(
-              "valueOf", containsPattern("Prefer `String#valueOf` over `String#format`"))
-          .expectErrorMessage("join", containsPattern("Prefer `String#join` over `String#format`"));
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(StringJoin.class, getClass());
-
   @Test
   void identification() {
-    compilationHelper
+    CompilationTestHelper.newInstance(StringJoin.class, getClass())
+        .expectErrorMessage(
+            "valueOf", containsPattern("Prefer `String#valueOf` over `String#format`"))
+        .expectErrorMessage("join", containsPattern("Prefer `String#join` over `String#format`"))
         .addSourceLines(
             "A.java",
             "import java.util.Formattable;",
@@ -63,7 +58,7 @@ final class StringJoinTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(StringJoin.class, getClass())
         .addInputLines(
             "A.java",
             "class A {",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/TimeZoneUsageTest.java

@@ -4,12 +4,9 @@ import com.google.errorprone.CompilationTestHelper;
 import org.junit.jupiter.api.Test;
 
 final class TimeZoneUsageTest {
-  private final CompilationTestHelper compilationHelper =
-      CompilationTestHelper.newInstance(TimeZoneUsage.class, getClass());
-
   @Test
   void identification() {
-    compilationHelper
+    CompilationTestHelper.newInstance(TimeZoneUsage.class, getClass())
         .addSourceLines(
             "A.java",
             "import static java.time.ZoneOffset.UTC;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/util/ConflictDetectionTest.java

@@ -0,0 +1,73 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.CompilationTestHelper;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.MethodTree;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import org.junit.jupiter.api.Test;
+
+final class ConflictDetectionTest {
+  @Test
+  void matcher() {
+    CompilationTestHelper.newInstance(RenameBlockerFlagger.class, getClass())
+        .addSourceLines(
+            "pkg/A.java",
+            "package pkg;",
+            "",
+            "import static pkg.A.B.method3t;",
+            "",
+            "import pkg.A.method4t;",
+            "",
+            "class A {",
+            "  void method1() {",
+            "    method3t();",
+            "    method4(method4t.class);",
+            "  }",
+            "",
+            "  // BUG: Diagnostic contains: a method named `method2t` is already defined in this class or a",
+            "  // supertype",
+            "  void method2() {}",
+            "",
+            "  void method2t() {}",
+            "",
+            "  // BUG: Diagnostic contains: `method3t` is already statically imported",
+            "  void method3() {}",
+            "",
+            "  void method4(Object o) {}",
+            "",
+            "  // BUG: Diagnostic contains: `int` is not a valid identifier",
+            "  void in() {}",
+            "",
+            "  static class B {",
+            "    static void method3t() {}",
+            "  }",
+            "",
+            "  class method4t {}",
+            "}")
+        .doTest();
+  }
+
+  /**
+   * A {@link BugChecker} that uses {@link ConflictDetection#findMethodRenameBlocker(MethodSymbol,
+   * String, VisitorState)} to flag methods of which the name cannot be suffixed with a {@code t}.
+   */
+  @BugPattern(summary = "Interacts with `ConflictDetection` for testing purposes", severity = ERROR)
+  public static final class RenameBlockerFlagger extends BugChecker implements MethodTreeMatcher {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public Description matchMethod(MethodTree tree, VisitorState state) {
+      return ConflictDetection.findMethodRenameBlocker(
+              ASTHelpers.getSymbol(tree), tree.getName() + "t", state)
+          .map(blocker -> buildDescription(tree).setMessage(blocker).build())
+          .orElse(Description.NO_MATCH);
+    }
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/util/FlagsTest.java

@@ -0,0 +1,31 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.ErrorProneOptions;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+final class FlagsTest {
+  private static Stream<Arguments> getListTestCases() {
+    /* { args, flag, expected } */
+    return Stream.of(
+        arguments(ImmutableList.of(), "Foo", ImmutableList.of()),
+        arguments(ImmutableList.of("-XepOpt:Foo=bar,baz"), "Qux", ImmutableList.of()),
+        arguments(ImmutableList.of("-XepOpt:Foo="), "Foo", ImmutableList.of()),
+        arguments(ImmutableList.of("-XepOpt:Foo=bar"), "Foo", ImmutableList.of("bar")),
+        arguments(ImmutableList.of("-XepOpt:Foo=bar,baz"), "Foo", ImmutableList.of("bar", "baz")),
+        arguments(ImmutableList.of("-XepOpt:Foo=,"), "Foo", ImmutableList.of("", "")));
+  }
+
+  @MethodSource("getListTestCases")
+  @ParameterizedTest
+  void getList(ImmutableList<String> args, String flag, ImmutableList<String> expected) {
+    assertThat(Flags.getList(ErrorProneOptions.processArgs(args).getFlags(), flag))
+        .containsExactlyElementsOf(expected);
+  }
+}

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/util/MethodMatcherFactoryTest.java

@@ -40,9 +40,6 @@ final class MethodMatcherFactoryTest {
                   "com.example.A#m2(java.lang.String)",
                   "com.example.sub.B#m3(int,int)"));
 
-  private final CompilationTestHelper compilationTestHelper =
-      CompilationTestHelper.newInstance(MatchedMethodsFlagger.class, getClass());
-
   @Test
   void createWithMalformedSignatures() {
     MethodMatcherFactory factory = new MethodMatcherFactory();
@@ -58,7 +55,7 @@ final class MethodMatcherFactoryTest {
 
   @Test
   void matcher() {
-    compilationTestHelper
+    CompilationTestHelper.newInstance(MatchedMethodsFlagger.class, getClass())
         .addSourceLines(
             "com/example/A.java",
             "package com.example;",

error-prone-contrib/src/test/java/tech/picnic/errorprone/refasterrules/RefasterRulesTest.java

@@ -49,7 +49,9 @@ final class RefasterRulesTest {
           ImmutableSortedMultisetRules.class,
           ImmutableSortedSetRules.class,
           IntStreamRules.class,
+          JooqRules.class,
           JUnitRules.class,
+          JUnitToAssertJRules.class,
           LongStreamRules.class,
           MapEntryRules.class,
           MapRules.class,

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JUnitToAssertJRulesTestInput.java

@@ -0,0 +1,173 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrowsExactly;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.google.common.collect.ImmutableSet;
+import org.junit.jupiter.api.Assertions;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<?> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(
+        Assertions.class,
+        assertDoesNotThrow(() -> null),
+        assertInstanceOf(null, null),
+        assertThrows(null, null),
+        assertThrowsExactly(null, null),
+        (Runnable) () -> assertFalse(true),
+        (Runnable) () -> assertNotNull(null),
+        (Runnable) () -> assertNotSame(null, null),
+        (Runnable) () -> assertNull(null),
+        (Runnable) () -> assertSame(null, null),
+        (Runnable) () -> assertTrue(true));
+  }
+
+  void testThrowNewAssertionError() {
+    Assertions.fail();
+  }
+
+  Object testFailWithMessage() {
+    return Assertions.fail("foo");
+  }
+
+  Object testFailWithMessageAndThrowable() {
+    return Assertions.fail("foo", new IllegalStateException());
+  }
+
+  void testFailWithThrowable() {
+    Assertions.fail(new IllegalStateException());
+  }
+
+  void testAssertThatIsTrue() {
+    assertTrue(true);
+  }
+
+  void testAssertThatWithFailMessageStringIsTrue() {
+    assertTrue(true, "foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsTrue() {
+    assertTrue(true, () -> "foo");
+  }
+
+  void testAssertThatIsFalse() {
+    assertFalse(true);
+  }
+
+  void testAssertThatWithFailMessageStringIsFalse() {
+    assertFalse(true, "foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsFalse() {
+    assertFalse(true, () -> "foo");
+  }
+
+  void testAssertThatIsNull() {
+    assertNull(new Object());
+  }
+
+  void testAssertThatWithFailMessageStringIsNull() {
+    assertNull(new Object(), "foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNull() {
+    assertNull(new Object(), () -> "foo");
+  }
+
+  void testAssertThatIsNotNull() {
+    assertNotNull(new Object());
+  }
+
+  void testAssertThatWithFailMessageStringIsNotNull() {
+    assertNotNull(new Object(), "foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNotNull() {
+    assertNotNull(new Object(), () -> "foo");
+  }
+
+  void testAssertThatIsSameAs() {
+    assertSame("foo", "bar");
+  }
+
+  void testAssertThatWithFailMessageStringIsSameAs() {
+    assertSame("foo", "bar", "baz");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsSameAs() {
+    assertSame("foo", "bar", () -> "baz");
+  }
+
+  void testAssertThatIsNotSameAs() {
+    assertNotSame("foo", "bar");
+  }
+
+  void testAssertThatWithFailMessageStringIsNotSameAs() {
+    assertNotSame("foo", "bar", "baz");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNotSameAs() {
+    assertNotSame("foo", "bar", () -> "baz");
+  }
+
+  void testAssertThatThrownByIsExactlyInstanceOf() {
+    assertThrowsExactly(IllegalStateException.class, () -> {});
+  }
+
+  void testAssertThatThrownByWithFailMessageStringIsExactlyInstanceOf() {
+    assertThrowsExactly(IllegalStateException.class, () -> {}, "foo");
+  }
+
+  void testAssertThatThrownByWithFailMessageSupplierIsExactlyInstanceOf() {
+    assertThrowsExactly(IllegalStateException.class, () -> {}, () -> "foo");
+  }
+
+  void testAssertThatThrownByIsInstanceOf() {
+    assertThrows(IllegalStateException.class, () -> {});
+  }
+
+  void testAssertThatThrownByWithFailMessageStringIsInstanceOf() {
+    assertThrows(IllegalStateException.class, () -> {}, "foo");
+  }
+
+  void testAssertThatThrownByWithFailMessageSupplierIsInstanceOf() {
+    assertThrows(IllegalStateException.class, () -> {}, () -> "foo");
+  }
+
+  void testAssertThatCodeDoesNotThrowAnyException() {
+    assertDoesNotThrow(() -> {});
+    assertDoesNotThrow(() -> toString());
+  }
+
+  void testAssertThatCodeWithFailMessageStringDoesNotThrowAnyException() {
+    assertDoesNotThrow(() -> {}, "foo");
+    assertDoesNotThrow(() -> toString(), "bar");
+  }
+
+  void testAssertThatCodeWithFailMessageSupplierDoesNotThrowAnyException() {
+    assertDoesNotThrow(() -> {}, () -> "foo");
+    assertDoesNotThrow(() -> toString(), () -> "bar");
+  }
+
+  void testAssertThatIsInstanceOf() {
+    assertInstanceOf(Object.class, new Object());
+  }
+
+  void testAssertThatWithFailMessageStringIsInstanceOf() {
+    assertInstanceOf(Object.class, new Object(), "foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsInstanceOf() {
+    assertInstanceOf(Object.class, new Object(), () -> "foo");
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JUnitToAssertJRulesTestOutput.java

@@ -0,0 +1,183 @@
+package tech.picnic.errorprone.refasterrules;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.fail;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrowsExactly;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.google.common.collect.ImmutableSet;
+import org.junit.jupiter.api.Assertions;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class JUnitToAssertJRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<?> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(
+        Assertions.class,
+        assertDoesNotThrow(() -> null),
+        assertInstanceOf(null, null),
+        assertThrows(null, null),
+        assertThrowsExactly(null, null),
+        (Runnable) () -> assertFalse(true),
+        (Runnable) () -> assertNotNull(null),
+        (Runnable) () -> assertNotSame(null, null),
+        (Runnable) () -> assertNull(null),
+        (Runnable) () -> assertSame(null, null),
+        (Runnable) () -> assertTrue(true));
+  }
+
+  void testThrowNewAssertionError() {
+    throw new AssertionError();
+  }
+
+  Object testFailWithMessage() {
+    return fail("foo");
+  }
+
+  Object testFailWithMessageAndThrowable() {
+    return fail("foo", new IllegalStateException());
+  }
+
+  void testFailWithThrowable() {
+    throw new AssertionError(new IllegalStateException());
+  }
+
+  void testAssertThatIsTrue() {
+    assertThat(true).isTrue();
+  }
+
+  void testAssertThatWithFailMessageStringIsTrue() {
+    assertThat(true).withFailMessage("foo").isTrue();
+  }
+
+  void testAssertThatWithFailMessageSupplierIsTrue() {
+    assertThat(true).withFailMessage(() -> "foo").isTrue();
+  }
+
+  void testAssertThatIsFalse() {
+    assertThat(true).isFalse();
+  }
+
+  void testAssertThatWithFailMessageStringIsFalse() {
+    assertThat(true).withFailMessage("foo").isFalse();
+  }
+
+  void testAssertThatWithFailMessageSupplierIsFalse() {
+    assertThat(true).withFailMessage(() -> "foo").isFalse();
+  }
+
+  void testAssertThatIsNull() {
+    assertThat(new Object()).isNull();
+  }
+
+  void testAssertThatWithFailMessageStringIsNull() {
+    assertThat(new Object()).withFailMessage("foo").isNull();
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNull() {
+    assertThat(new Object()).withFailMessage(() -> "foo").isNull();
+  }
+
+  void testAssertThatIsNotNull() {
+    assertThat(new Object()).isNotNull();
+  }
+
+  void testAssertThatWithFailMessageStringIsNotNull() {
+    assertThat(new Object()).withFailMessage("foo").isNotNull();
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNotNull() {
+    assertThat(new Object()).withFailMessage(() -> "foo").isNotNull();
+  }
+
+  void testAssertThatIsSameAs() {
+    assertThat("bar").isSameAs("foo");
+  }
+
+  void testAssertThatWithFailMessageStringIsSameAs() {
+    assertThat("bar").withFailMessage("baz").isSameAs("foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsSameAs() {
+    assertThat("bar").withFailMessage(() -> "baz").isSameAs("foo");
+  }
+
+  void testAssertThatIsNotSameAs() {
+    assertThat("bar").isNotSameAs("foo");
+  }
+
+  void testAssertThatWithFailMessageStringIsNotSameAs() {
+    assertThat("bar").withFailMessage("baz").isNotSameAs("foo");
+  }
+
+  void testAssertThatWithFailMessageSupplierIsNotSameAs() {
+    assertThat("bar").withFailMessage(() -> "baz").isNotSameAs("foo");
+  }
+
+  void testAssertThatThrownByIsExactlyInstanceOf() {
+    assertThatThrownBy(() -> {}).isExactlyInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatThrownByWithFailMessageStringIsExactlyInstanceOf() {
+    assertThatThrownBy(() -> {})
+        .withFailMessage("foo")
+        .isExactlyInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatThrownByWithFailMessageSupplierIsExactlyInstanceOf() {
+    assertThatThrownBy(() -> {})
+        .withFailMessage(() -> "foo")
+        .isExactlyInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatThrownByIsInstanceOf() {
+    assertThatThrownBy(() -> {}).isInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatThrownByWithFailMessageStringIsInstanceOf() {
+    assertThatThrownBy(() -> {}).withFailMessage("foo").isInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatThrownByWithFailMessageSupplierIsInstanceOf() {
+    assertThatThrownBy(() -> {})
+        .withFailMessage(() -> "foo")
+        .isInstanceOf(IllegalStateException.class);
+  }
+
+  void testAssertThatCodeDoesNotThrowAnyException() {
+    assertThatCode(() -> {}).doesNotThrowAnyException();
+    assertThatCode(() -> toString()).doesNotThrowAnyException();
+  }
+
+  void testAssertThatCodeWithFailMessageStringDoesNotThrowAnyException() {
+    assertThatCode(() -> {}).withFailMessage("foo").doesNotThrowAnyException();
+    assertThatCode(() -> toString()).withFailMessage("bar").doesNotThrowAnyException();
+  }
+
+  void testAssertThatCodeWithFailMessageSupplierDoesNotThrowAnyException() {
+    assertThatCode(() -> {}).withFailMessage(() -> "foo").doesNotThrowAnyException();
+    assertThatCode(() -> toString()).withFailMessage(() -> "bar").doesNotThrowAnyException();
+  }
+
+  void testAssertThatIsInstanceOf() {
+    assertThat(new Object()).isInstanceOf(Object.class);
+  }
+
+  void testAssertThatWithFailMessageStringIsInstanceOf() {
+    assertThat(new Object()).withFailMessage("foo").isInstanceOf(Object.class);
+  }
+
+  void testAssertThatWithFailMessageSupplierIsInstanceOf() {
+    assertThat(new Object()).withFailMessage(() -> "foo").isInstanceOf(Object.class);
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JooqRulesTestInput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.refasterrules;
+
+import java.util.stream.Stream;
+import org.jooq.impl.DSL;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class JooqRulesTest implements RefasterRuleCollectionTestCase {
+  Stream<?> testResultQueryFetchStream() {
+    return DSL.select().stream();
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/JooqRulesTestOutput.java

@@ -0,0 +1,11 @@
+package tech.picnic.errorprone.refasterrules;
+
+import java.util.stream.Stream;
+import org.jooq.impl.DSL;
+import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
+
+final class JooqRulesTest implements RefasterRuleCollectionTestCase {
+  Stream<?> testResultQueryFetchStream() {
+    return DSL.select().fetch().stream();
+  }
+}

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestInput.java

@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.math.RoundingMode;
@@ -11,7 +13,7 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class MapRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(HashMap.class);
+    return ImmutableSet.of(HashMap.class, requireNonNullElse(null, null));
   }
 
   Map<RoundingMode, String> testCreateEnumMap() {
@@ -22,6 +24,10 @@ final class MapRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableMap.of(1, "foo").getOrDefault("bar", null);
   }
 
+  String testMapGetOrDefault() {
+    return requireNonNullElse(ImmutableMap.of(1, "foo").get("bar"), "baz");
+  }
+
   ImmutableSet<Boolean> testMapIsEmpty() {
     return ImmutableSet.of(
         ImmutableMap.of("foo", 1).keySet().isEmpty(),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/MapRulesTestOutput.java

@@ -1,5 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Objects.requireNonNullElse;
+
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.math.RoundingMode;
@@ -12,7 +14,7 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class MapRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(HashMap.class);
+    return ImmutableSet.of(HashMap.class, requireNonNullElse(null, null));
   }
 
   Map<RoundingMode, String> testCreateEnumMap() {
@@ -23,6 +25,10 @@ final class MapRulesTest implements RefasterRuleCollectionTestCase {
     return ImmutableMap.of(1, "foo").get("bar");
   }
 
+  String testMapGetOrDefault() {
+    return ImmutableMap.of(1, "foo").getOrDefault("bar", "baz");
+  }
+
   ImmutableSet<Boolean> testMapIsEmpty() {
     return ImmutableSet.of(
         ImmutableMap.of("foo", 1).isEmpty(),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/NullRulesTestInput.java

@@ -3,13 +3,14 @@ package tech.picnic.errorprone.refasterrules;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class NullRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(MoreObjects.class);
+    return ImmutableSet.of(MoreObjects.class, Optional.class);
   }
 
   boolean testIsNull() {
@@ -20,8 +21,13 @@ final class NullRulesTest implements RefasterRuleCollectionTestCase {
     return Objects.nonNull("foo");
   }
 
-  String testRequireNonNullElse() {
-    return MoreObjects.firstNonNull("foo", "bar");
+  ImmutableSet<String> testRequireNonNullElse() {
+    return ImmutableSet.of(
+        MoreObjects.firstNonNull("foo", "bar"), Optional.ofNullable("baz").orElse("qux"));
+  }
+
+  String testRequireNonNullElseGet() {
+    return Optional.ofNullable("foo").orElseGet(() -> "bar");
   }
 
   long testIsNullFunction() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/NullRulesTestOutput.java

@@ -1,17 +1,19 @@
 package tech.picnic.errorprone.refasterrules;
 
 import static java.util.Objects.requireNonNullElse;
+import static java.util.Objects.requireNonNullElseGet;
 
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 
 final class NullRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(MoreObjects.class);
+    return ImmutableSet.of(MoreObjects.class, Optional.class);
   }
 
   boolean testIsNull() {
@@ -22,8 +24,12 @@ final class NullRulesTest implements RefasterRuleCollectionTestCase {
     return "foo" != null;
   }
 
-  String testRequireNonNullElse() {
-    return requireNonNullElse("foo", "bar");
+  ImmutableSet<String> testRequireNonNullElse() {
+    return ImmutableSet.of(requireNonNullElse("foo", "bar"), requireNonNullElse("baz", "qux"));
+  }
+
+  String testRequireNonNullElseGet() {
+    return requireNonNullElseGet("foo", () -> "bar");
   }
 
   long testIsNullFunction() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java

@@ -116,7 +116,11 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
-    return ImmutableSet.of(Mono.just(1).switchIfEmpty(Mono.empty()), Mono.<Void>empty().then());
+    return ImmutableSet.of(
+        Mono.just(1).switchIfEmpty(Mono.empty()),
+        Mono.just(2).flux().next(),
+        Mono.just(3).flux().singleOrEmpty(),
+        Mono.<Void>empty().then());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java

@@ -121,7 +121,7 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
   }
 
   ImmutableSet<Mono<?>> testMonoIdentity() {
-    return ImmutableSet.of(Mono.just(1), Mono.<Void>empty());
+    return ImmutableSet.of(Mono.just(1), Mono.just(2), Mono.just(3), Mono.<Void>empty());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/TestNGToAssertJRulesTestInput.java

@@ -24,7 +24,7 @@ final class TestNGToAssertJRulesTest implements RefasterRuleCollectionTestCase {
   public ImmutableSet<?> elidedTypesAndStaticImports() {
     return ImmutableSet.of(
         (Runnable) () -> assertEquals(new byte[0], null),
-        (Runnable) () -> assertEqualsNoOrder(null, null),
+        (Runnable) () -> assertEqualsNoOrder((Object[]) null, null),
         (Runnable) () -> assertFalse(true),
         (Runnable) () -> assertNotEquals(new byte[0], null),
         (Runnable) () -> assertNotNull(null),

error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/TestNGToAssertJRulesTestOutput.java

@@ -29,7 +29,7 @@ final class TestNGToAssertJRulesTest implements RefasterRuleCollectionTestCase {
   public ImmutableSet<?> elidedTypesAndStaticImports() {
     return ImmutableSet.of(
         (Runnable) () -> assertEquals(new byte[0], null),
-        (Runnable) () -> assertEqualsNoOrder(null, null),
+        (Runnable) () -> assertEqualsNoOrder((Object[]) null, null),
         (Runnable) () -> assertFalse(true),
         (Runnable) () -> assertNotEquals(new byte[0], null),
         (Runnable) () -> assertNotNull(null),

pom.xml

@@ -4,7 +4,7 @@
 
     <groupId>tech.picnic.error-prone-support</groupId>
     <artifactId>error-prone-support</artifactId>
-    <version>0.6.1-SNAPSHOT</version>
+    <version>0.8.1-SNAPSHOT</version>
     <packaging>pom</packaging>
 
     <name>Picnic :: Error Prone Support</name>
@@ -39,6 +39,7 @@
     </developers>
 
     <modules>
+        <module>documentation-support</module>
         <module>error-prone-contrib</module>
         <module>refaster-compiler</module>
         <module>refaster-runner</module>
@@ -148,16 +149,16 @@
         <version.auto-service>1.0.1</version.auto-service>
         <version.auto-value>1.10.1</version.auto-value>
         <version.error-prone>${version.error-prone-orig}</version.error-prone>
-        <version.error-prone-fork>v${version.error-prone-orig}-picnic-2</version.error-prone-fork>
-        <version.error-prone-orig>2.16</version.error-prone-orig>
-        <version.error-prone-slf4j>0.1.16</version.error-prone-slf4j>
+        <version.error-prone-fork>v${version.error-prone-orig}-picnic-1</version.error-prone-fork>
+        <version.error-prone-orig>2.18.0</version.error-prone-orig>
+        <version.error-prone-slf4j>0.1.18</version.error-prone-slf4j>
         <version.guava-beta-checker>1.0</version.guava-beta-checker>
         <version.jdk>11</version.jdk>
-        <version.maven>3.8.6</version.maven>
-        <version.mockito>4.11.0</version.mockito>
+        <version.maven>3.8.7</version.maven>
+        <version.mockito>5.1.1</version.mockito>
         <version.nopen-checker>1.0.1</version.nopen-checker>
-        <version.nullaway>0.10.5</version.nullaway>
-        <version.pitest-git>1.0.3</version.pitest-git>
+        <version.nullaway>0.10.9</version.nullaway>
+        <version.pitest-git>1.0.4</version.pitest-git>
         <version.surefire>2.22.2</version.surefire>
     </properties>
 
@@ -188,6 +189,11 @@
                 <artifactId>error_prone_test_helpers</artifactId>
                 <version>${version.error-prone}</version>
             </dependency>
+            <dependency>
+                <groupId>${project.groupId}</groupId>
+                <artifactId>documentation-support</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                 <groupId>${project.groupId}</groupId>
                 <artifactId>refaster-compiler</artifactId>
@@ -211,7 +217,7 @@
             <dependency>
                 <groupId>com.fasterxml.jackson</groupId>
                 <artifactId>jackson-bom</artifactId>
-                <version>2.14.1</version>
+                <version>2.14.2</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -269,7 +275,7 @@
             <dependency>
                 <groupId>com.newrelic.agent.java</groupId>
                 <artifactId>newrelic-api</artifactId>
-                <version>7.11.1</version>
+                <version>8.0.0</version>
             </dependency>
             <!-- Specified as a workaround for
             https://github.com/mojohaus/versions-maven-plugin/issues/244. -->
@@ -281,7 +287,7 @@
             <dependency>
                 <groupId>io.projectreactor</groupId>
                 <artifactId>reactor-bom</artifactId>
-                <version>2022.0.1</version>
+                <version>2022.0.2</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -298,7 +304,7 @@
             <dependency>
                 <groupId>io.swagger.core.v3</groupId>
                 <artifactId>swagger-annotations</artifactId>
-                <version>2.2.7</version>
+                <version>2.2.8</version>
             </dependency>
             <dependency>
                 <groupId>jakarta.servlet</groupId>
@@ -322,6 +328,11 @@
                 <artifactId>junit</artifactId>
                 <version>4.13.2</version>
             </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy</artifactId>
+                <version>1.13.0</version>
+            </dependency>
             <!-- Specified so that Renovate will file Maven upgrade PRs, which
             subsequently will cause `maven-enforcer-plugin` to require that
             developers build the project using the latest Maven release. -->
@@ -337,13 +348,15 @@
             </dependency>
             <dependency>
                 <groupId>org.assertj</groupId>
-                <artifactId>assertj-core</artifactId>
-                <version>3.23.1</version>
+                <artifactId>assertj-bom</artifactId>
+                <version>3.24.2</version>
+                <type>pom</type>
+                <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.checkerframework</groupId>
                 <artifactId>checker-qual</artifactId>
-                <version>3.28.0</version>
+                <version>3.30.0</version>
             </dependency>
             <dependency>
                 <groupId>org.hamcrest</groupId>
@@ -355,6 +368,11 @@
                 <artifactId>value-annotations</artifactId>
                 <version>2.9.3</version>
             </dependency>
+            <dependency>
+                <groupId>org.jooq</groupId>
+                <artifactId>jooq</artifactId>
+                <version>3.16.14</version>
+            </dependency>
             <dependency>
                 <groupId>org.jspecify</groupId>
                 <artifactId>jspecify</artifactId>
@@ -363,7 +381,7 @@
             <dependency>
                 <groupId>org.junit</groupId>
                 <artifactId>junit-bom</artifactId>
-                <version>5.9.1</version>
+                <version>5.9.2</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -382,19 +400,19 @@
             <dependency>
                 <groupId>org.springframework</groupId>
                 <artifactId>spring-framework-bom</artifactId>
-                <version>5.3.24</version>
+                <version>5.3.25</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-test</artifactId>
-                <version>2.7.7</version>
+                <version>2.7.8</version>
             </dependency>
             <dependency>
                 <groupId>org.testng</groupId>
                 <artifactId>testng</artifactId>
-                <version>7.4.0</version>
+                <version>7.7.1</version>
             </dependency>
         </dependencies>
     </dependencyManagement>
@@ -405,7 +423,7 @@
                 <plugin>
                     <groupId>com.github.ekryd.sortpom</groupId>
                     <artifactId>sortpom-maven-plugin</artifactId>
-                    <version>3.2.0</version>
+                    <version>3.2.1</version>
                     <configuration>
                         <createBackupFile>false</createBackupFile>
                         <encoding>${project.build.sourceEncoding}</encoding>
@@ -520,7 +538,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-checkstyle-plugin</artifactId>
-                    <version>3.2.0</version>
+                    <version>3.2.1</version>
                     <configuration>
                         <checkstyleRules>
                             <!-- We only enable rules that are not enforced by
@@ -686,10 +704,6 @@
                                             <!-- Instead, please use
                                             `com.google.common.collect.Streams`. -->
                                         </property>
-                                        <property name="illegalClasses" value="org\.junit\.jupiter\.api\.Assertions(\..*?)?">
-                                            <!-- Instead, please use
-                                            `org.assertj.core.api.Assertions`. -->
-                                        </property>
                                         <property name="illegalClasses" value="org\.springframework\.stereotype\.(Component|Controller|Service)">
                                             <!-- We don't use Spring's
                                             component scanning, so `@Component`
@@ -712,6 +726,9 @@
                                     <module name="InnerAssignment" />
                                     <module name="InvalidJavadocPosition" />
                                     <module name="JavadocBlockTagLocation" />
+                                    <module name="JavadocStyle">
+                                        <property name="checkEmptyJavadoc" value="true" />
+                                    </module>
                                     <module name="LocalVariableName" />
                                     <module name="MatchXpath">
                                         <property name="query" value="//BLOCK_COMMENT_BEGIN[./COMMENT_CONTENT[contains(@text, '@author')]]" />
@@ -771,12 +788,12 @@
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>10.5.0</version>
+                            <version>10.7.0</version>
                         </dependency>
                         <dependency>
                             <groupId>io.spring.nohttp</groupId>
                             <artifactId>nohttp-checkstyle</artifactId>
-                            <version>0.0.10</version>
+                            <version>0.0.11</version>
                         </dependency>
                     </dependencies>
                     <executions>
@@ -850,6 +867,7 @@
                         </annotationProcessorPaths>
                         <compilerArgs>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
+                            <arg>--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED</arg>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED</arg>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</arg>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED</arg>
@@ -871,7 +889,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-dependency-plugin</artifactId>
-                    <version>3.4.0</version>
+                    <version>3.5.0</version>
                     <configuration>
                         <!-- XXX: Drop `ignoreAllNonTestScoped` once
                         https://issues.apache.org/jira/browse/MNG-6058 is
@@ -886,7 +904,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-deploy-plugin</artifactId>
-                    <version>3.0.0</version>
+                    <version>3.1.0</version>
                     <configuration>
                         <retryFailedDeploymentCount>3</retryFailedDeploymentCount>
                     </configuration>
@@ -894,12 +912,41 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-enforcer-plugin</artifactId>
-                    <version>3.1.0</version>
+                    <version>3.2.1</version>
                     <configuration>
                         <fail>false</fail>
                         <rules>
+                            <banCircularDependencies />
+                            <banDependencyManagementScope />
+                            <banDuplicateClasses>
+                                <dependencies>
+                                    <dependency>
+                                        <groupId>org.checkerframework</groupId>
+                                        <artifactId>dataflow-errorprone</artifactId>
+                                        <!-- This package is contained in
+                                        Checker Framework's `checker-qual` and
+                                        `dataflow-errorprone` modules. Error
+                                        Prone requires the latter, while Guava
+                                        pulls in the former. Since the package
+                                        contains mostly annotations, this is
+                                        not expected to cause trouble in
+                                        practice. -->
+                                        <ignoreClasses>
+                                            <ignoreClass>org.checkerframework.dataflow.qual.*</ignoreClass>
+                                        </ignoreClasses>
+                                    </dependency>
+                                </dependencies>
+                                <findAllDuplicates>true</findAllDuplicates>
+                            </banDuplicateClasses>
                             <banDuplicatePomDependencyVersions />
+                            <!-- XXX: Enable this rule once it no longer
+                            "downloads the internet". See
+                            https://issues.apache.org/jira/browse/MENFORCER-467.
+                            <banDynamicVersions />-->
                             <dependencyConvergence />
+                            <enforceBytecodeVersion>
+                                <maxJdkVersion>${version.jdk}</maxJdkVersion>
+                            </enforceBytecodeVersion>
                             <requireEncoding>
                                 <acceptAsciiSubset>true</acceptAsciiSubset>
                                 <encoding>ISO-8859-1</encoding>
@@ -911,8 +958,8 @@
                             <requireMavenVersion>
                                 <version>${version.maven}</version>
                             </requireMavenVersion>
+                            <requireNoRepositories />
                             <requirePluginVersions />
-                            <requireSameVersionsReactor />
                             <requireUpperBoundDeps>
                                 <excludes>
                                     <!-- XXX:
@@ -1136,6 +1183,8 @@
                                 | BSD 3-clause
                                 | BSD License 3
                                 | Eclipse Distribution License (New BSD License)
+                                | Eclipse Distribution License - v 1.0
+                                | EDL 1.0
                                 | New BSD License
                             </licenseMerge>
                             <licenseMerge>
@@ -1241,7 +1290,7 @@
                 <plugin>
                     <groupId>org.pitest</groupId>
                     <artifactId>pitest-maven</artifactId>
-                    <version>1.10.3</version>
+                    <version>1.11.0</version>
                     <configuration>
                         <excludedClasses>
                             <!-- AutoValue generated classes. -->
@@ -1280,7 +1329,7 @@
                         <dependency>
                             <groupId>org.pitest</groupId>
                             <artifactId>pitest-junit5-plugin</artifactId>
-                            <version>1.1.0</version>
+                            <version>1.1.2</version>
                         </dependency>
                     </dependencies>
                     <executions>
@@ -1334,6 +1383,30 @@
             <build>
                 <pluginManagement>
                     <plugins>
+                        <plugin>
+                            <groupId>org.apache.maven.plugins</groupId>
+                            <artifactId>maven-enforcer-plugin</artifactId>
+                            <configuration>
+                                <rules>
+                                    <banDuplicateClasses>
+                                        <!-- The original
+                                        `error_prone_annotations` dependency
+                                        contains the same classes as those
+                                        provided by the corresponding Picnic
+                                        Error Prone fork artifact. -->
+                                        <dependencies combine.children="append">
+                                            <dependency>
+                                                <groupId>com.google.errorprone</groupId>
+                                                <artifactId>error_prone_annotations</artifactId>
+                                                <ignoreClasses>
+                                                    <ignoreClass>*</ignoreClass>
+                                                </ignoreClasses>
+                                            </dependency>
+                                        </dependencies>
+                                    </banDuplicateClasses>
+                                </rules>
+                            </configuration>
+                        </plugin>
                         <plugin>
                             <groupId>org.apache.maven.plugins</groupId>
                             <artifactId>maven-surefire-plugin</artifactId>
@@ -1577,6 +1650,10 @@
                                     <!-- XXX: Enable this once we open-source
                                     this library. -->
                                     -Xep:BetaApi:OFF
+                                    <!-- XXX: Enable once compatible with
+                                    `UnnecessarilyVisible`. See
+                                    https://github.com/google/error-prone/issues/3706. -->
+                                    -Xep:InjectOnBugCheckers:OFF
                                     <!-- We don't target JDK 7. -->
                                     -Xep:Java7ApiChecker:OFF
                                     <!-- We don't target JDK 8. -->
@@ -1585,6 +1662,9 @@
                                     -Xep:StaticOrDefaultInterfaceMethod:OFF
                                     <!-- We generally discourage `var` use. -->
                                     -Xep:Varifier:OFF
+                                    <!-- Yoda conditions are not always more
+                                    readable than the alternative. -->
+                                    -Xep:YodaCondition:OFF
                                     -XepOpt:CheckReturnValue:CheckAllConstructors=true
                                     <!-- XXX: Enable once there are fewer
                                     false-positives.
@@ -1594,6 +1674,10 @@
                                     -XepOpt:NullAway:AssertsEnabled=true
                                     -XepOpt:NullAway:CheckOptionalEmptiness=true
                                     -XepOpt:Nullness:Conservative=false
+                                    <!-- XXX: Enable once this check respects
+                                    the compilation source version. See
+                                    https://github.com/google/error-prone/pull/3646.
+                                    -XepOpt:StatementSwitchToExpressionSwitch:EnableDirectConversion=true -->
                                     <!-- Append additional custom arguments. -->
                                     ${error-prone.patch-args}
                                     ${error-prone.self-check-args}

refaster-compiler/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.6.1-SNAPSHOT</version>
+        <version>0.8.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-compiler</artifactId>

refaster-runner/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.6.1-SNAPSHOT</version>
+        <version>0.8.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-runner</artifactId>

refaster-runner/src/main/java/tech/picnic/errorprone/refaster/runner/Refaster.java

@@ -161,6 +161,7 @@ public final class Refaster extends BugChecker implements CompilationUnitTreeMat
    * that could cause {@link VisitorState#reportMatch(Description)}} to override the reported
    * severity).
    */
+  @SuppressWarnings("RestrictedApiChecker" /* We create a heavily customized `Description` here. */)
   private static Description augmentDescription(
       Description description, Optional<SeverityLevel> severityOverride) {
     return Description.builder(

refaster-runner/src/test/java/tech/picnic/errorprone/refaster/runner/RefasterTest.java

@@ -50,12 +50,6 @@ final class RefasterTest {
                   "\\[Refaster Rule\\] FooRules\\.ExtraGrouping\\.StringOfSizeThreeRule: "
                       + "A custom description about matching three-char strings\\s+.+\\s+"
                       + "\\(see https://example.com/custom\\)"));
-  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(Refaster.class, getClass());
-  private final BugCheckerRefactoringTestHelper restrictedRefactoringTestHelper =
-      BugCheckerRefactoringTestHelper.newInstance(Refaster.class, getClass())
-          .setArgs(
-              "-XepOpt:Refaster:NamePattern=.*\\$(StringOfSizeZeroVerboseRule|StringOfSizeTwoRule)$");
 
   @Test
   void identification() {
@@ -220,7 +214,7 @@ final class RefasterTest {
 
   @Test
   void replacement() {
-    refactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(Refaster.class, getClass())
         .addInputLines(
             "A.java",
             "class A {",
@@ -246,7 +240,9 @@ final class RefasterTest {
 
   @Test
   void restrictedReplacement() {
-    restrictedRefactoringTestHelper
+    BugCheckerRefactoringTestHelper.newInstance(Refaster.class, getClass())
+        .setArgs(
+            "-XepOpt:Refaster:NamePattern=.*\\$(StringOfSizeZeroVerboseRule|StringOfSizeTwoRule)$")
         .addInputLines(
             "A.java",
             "class A {",

refaster-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.6.1-SNAPSHOT</version>
+        <version>0.8.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-support</artifactId>

refaster-support/src/main/java/tech/picnic/errorprone/refaster/AnnotatedCompositeCodeTransformer.java

@@ -77,6 +77,7 @@ public abstract class AnnotatedCompositeCodeTransformer implements CodeTransform
     }
   }
 
+  @SuppressWarnings("RestrictedApiChecker" /* We create a heavily customized `Description` here. */)
   private Description augmentDescription(
       Description description, CodeTransformer delegate, Context context) {
     String shortCheckName = getShortCheckName(description.checkName);

refaster-support/src/test/java/tech/picnic/errorprone/refaster/AnnotatedCompositeCodeTransformerTest.java

@@ -171,6 +171,7 @@ final class AnnotatedCompositeCodeTransformerTest {
     return description(name, Optional.of(""), WARNING, "");
   }
 
+  @SuppressWarnings("RestrictedApiChecker" /* We create a heavily customized `Description` here. */)
   private static Description description(
       String name, Optional<String> link, SeverityLevel severityLevel, String message) {
     return Description.builder(DUMMY_POSITION, name, link.orElse(null), severityLevel, message)

refaster-support/src/test/java/tech/picnic/errorprone/refaster/matchers/AbstractMatcherTestChecker.java

@@ -35,9 +35,7 @@ abstract class AbstractMatcherTestChecker extends BugChecker implements Compilat
       @Override
       public @Nullable Void scan(Tree tree, @Nullable Void unused) {
         if (tree instanceof ExpressionTree && delegate.matches((ExpressionTree) tree, state)) {
-          state.reportMatch(
-              Description.builder(tree, canonicalName(), null, defaultSeverity(), message())
-                  .build());
+          state.reportMatch(describeMatch(tree));
         }
 
         return super.scan(tree, unused);

refaster-test-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.6.1-SNAPSHOT</version>
+        <version>0.8.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-test-support</artifactId>

run-mutation-tests.sh

@@ -7,7 +7,7 @@
 set -e -u -o pipefail
 
 if [ "${#}" -gt 1 ]; then
-  echo "Usage: ./$(basename "${0}") [TargetTests]"
+  echo "Usage: ${0} [TargetTests]"
   exit 1
 fi
 

website/_includes/footer_custom.html

@@ -1,5 +1,5 @@
 <img src="/assets/images/picnic-logo@2x.png" alt="Picnic Logo" id="logo"/>
 
 <p>
-    Copyright &copy; 2017-2022 Picnic Technologies BV
+    Copyright &copy; 2017-2023 Picnic Technologies BV
 </p>