PSM-1474 Introduce Duplicate Expect Next Test

See:
- https://github.com/mockito/mockito/releases/tag/v4.11.0
- https://github.com/mockito/mockito/compare/v4.10.0...v4.11.0

.github/ISSUE_TEMPLATE/feature_request.md

@@ -17,23 +17,24 @@ you'd like to be solved through Error Prone Support. -->
 
 - [ ] Support a stylistic preference.
 - [ ] Avoid a common gotcha, or potential problem.
+- [ ] Improve performance.
 
 <!--
 Here, provide a clear and concise description of the desired change.
 
 If possible, provide a simple and minimal example using the following format:
-
-  I would like to rewrite the following code:
-  ```java
-  // XXX: Write the code to match here.
-  ```
-
-  to:
-  ```java
-  // XXX: Write the desired code here.
-  ```
 -->
 
+I would like to rewrite the following code:
+```java
+// XXX: Write the code to match here.
+```
+
+to:
+```java
+// XXX: Write the desired code here.
+```
+
 ### Considerations
 
 <!--

.github/workflows/build.yaml

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

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.5.1-SNAPSHOT</version>
+        <version>0.6.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>

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

@@ -32,7 +32,7 @@ import com.sun.source.util.SimpleTreeVisitor;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**

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

@@ -23,6 +23,7 @@ import com.google.errorprone.matchers.Matcher;
 import com.google.errorprone.util.ASTHelpers;
 import com.google.errorprone.util.ASTHelpers.TargetType;
 import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
@@ -32,7 +33,7 @@ import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /** A {@link BugChecker} that flags redundant identity conversions. */
 // XXX: Consider detecting cases where a flagged expression is passed to a method, and where removal
-// of the identify conversion would cause a different method overload to be selected. Depending on
+// of the identity conversion would cause a different method overload to be selected. Depending on
 // the target method such a modification may change the code's semantics or performance.
 @AutoService(BugChecker.class)
 @BugPattern(
@@ -45,6 +46,13 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
   private static final long serialVersionUID = 1L;
   private static final Matcher<ExpressionTree> IS_CONVERSION_METHOD =
       anyOf(
+          staticMethod()
+              .onClassAny(
+                  Primitives.allWrapperTypes().stream()
+                      .map(Class::getName)
+                      .collect(toImmutableSet()))
+              .named("valueOf"),
+          staticMethod().onClass(String.class.getName()).named("valueOf"),
           staticMethod()
               .onClassAny(
                   "com.google.common.collect.ImmutableBiMap",
@@ -60,12 +68,8 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
                   "com.google.common.collect.ImmutableTable")
               .named("copyOf"),
           staticMethod()
-              .onClassAny(
-                  Primitives.allWrapperTypes().stream()
-                      .map(Class::getName)
-                      .collect(toImmutableSet()))
-              .named("valueOf"),
-          staticMethod().onClass(String.class.getName()).named("valueOf"),
+              .onClass("com.google.errorprone.matchers.Matchers")
+              .namedAnyOf("allOf", "anyOf"),
           staticMethod().onClass("reactor.adapter.rxjava.RxJava2Adapter"),
           staticMethod()
               .onClass("reactor.core.publisher.Flux")
@@ -95,6 +99,15 @@ public final class IdentityConversion extends BugChecker implements MethodInvoca
       return Description.NO_MATCH;
     }
 
+    if (sourceType.isPrimitive()
+        && state.getPath().getParentPath().getLeaf() instanceof MemberSelectTree) {
+      /*
+       * The result of the conversion method is dereferenced, while the source type is a primitive:
+       * dropping the conversion would yield uncompilable code.
+       */
+      return Description.NO_MATCH;
+    }
+
     return buildDescription(tree)
         .setMessage(
             "This method invocation appears redundant; remove it or suppress this warning and "

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

@@ -6,15 +6,18 @@ import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.collect.Iterables;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
 import com.google.errorprone.bugpatterns.BugChecker.LambdaExpressionTreeMatcher;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.InstanceOfTree;
 import com.sun.source.tree.LambdaExpressionTree;
 import com.sun.source.tree.Tree.Kind;
+import com.sun.source.tree.VariableTree;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
@@ -39,15 +42,19 @@ public final class IsInstanceLambdaUsage extends BugChecker implements LambdaExp
 
   @Override
   public Description matchLambdaExpression(LambdaExpressionTree tree, VisitorState state) {
-    if (tree.getKind() != Kind.LAMBDA_EXPRESSION || tree.getBody().getKind() != Kind.INSTANCE_OF) {
+    if (tree.getParameters().size() != 1 || tree.getBody().getKind() != Kind.INSTANCE_OF) {
+      return Description.NO_MATCH;
+    }
+
+    VariableTree param = Iterables.getOnlyElement(tree.getParameters());
+    InstanceOfTree instanceOf = (InstanceOfTree) tree.getBody();
+    if (!ASTHelpers.getSymbol(param).equals(ASTHelpers.getSymbol(instanceOf.getExpression()))) {
       return Description.NO_MATCH;
     }
 
     return describeMatch(
         tree,
         SuggestedFix.replace(
-            tree,
-            SourceCode.treeToString(((InstanceOfTree) tree.getBody()).getType(), state)
-                + ".class::isInstance"));
+            tree, SourceCode.treeToString(instanceOf.getType(), state) + ".class::isInstance"));
   }
 }

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

@@ -3,21 +3,19 @@ package tech.picnic.errorprone.bugpatterns;
 import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
 import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
-import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
 import static com.google.errorprone.matchers.Matchers.allOf;
-import static com.google.errorprone.matchers.Matchers.annotations;
-import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.enclosingClass;
 import static com.google.errorprone.matchers.Matchers.hasModifier;
-import static com.google.errorprone.matchers.Matchers.isType;
+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.isReservedKeyword;
+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;
 
 import com.google.auto.service.AutoService;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -26,14 +24,15 @@ import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.fixes.SuggestedFixes;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
-import com.google.errorprone.matchers.Matchers;
 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.MoreASTHelpers;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /** A {@link BugChecker} that flags non-canonical JUnit method declarations. */
@@ -53,21 +52,19 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
   private static final long serialVersionUID = 1L;
   private static final String TEST_PREFIX = "test";
   private static final ImmutableSet<Modifier> ILLEGAL_MODIFIERS =
-      ImmutableSet.of(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC);
-  private static final Matcher<MethodTree> HAS_UNMODIFIABLE_SIGNATURE =
-      anyOf(
-          annotations(AT_LEAST_ONE, isType("java.lang.Override")),
-          allOf(
-              Matchers.not(hasModifier(Modifier.FINAL)),
-              Matchers.not(hasModifier(Modifier.PRIVATE)),
-              enclosingClass(hasModifier(Modifier.ABSTRACT))));
+      Sets.immutableEnumSet(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC);
+  private static final Matcher<MethodTree> IS_LIKELY_OVERRIDDEN =
+      allOf(
+          not(hasModifier(Modifier.FINAL)),
+          not(hasModifier(Modifier.PRIVATE)),
+          enclosingClass(hasModifier(Modifier.ABSTRACT)));
 
   /** Instantiates a new {@link JUnitMethodDeclaration} instance. */
   public JUnitMethodDeclaration() {}
 
   @Override
   public Description matchMethod(MethodTree tree, VisitorState state) {
-    if (HAS_UNMODIFIABLE_SIGNATURE.matches(tree, state)) {
+    if (IS_LIKELY_OVERRIDDEN.matches(tree, state) || isOverride(tree, state)) {
       return Description.NO_MATCH;
     }
 
@@ -89,10 +86,11 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
 
   private void suggestTestMethodRenameIfApplicable(
       MethodTree tree, SuggestedFix.Builder fixBuilder, VisitorState state) {
-    tryCanonicalizeMethodName(tree)
+    MethodSymbol symbol = ASTHelpers.getSymbol(tree);
+    tryCanonicalizeMethodName(symbol)
         .ifPresent(
             newName ->
-                findMethodRenameBlocker(newName, state)
+                findMethodRenameBlocker(symbol, newName, state)
                     .ifPresentOrElse(
                         blocker -> reportMethodRenameBlocker(tree, blocker, state),
                         () -> fixBuilder.merge(SuggestedFixes.renameMethod(tree, newName, state))));
@@ -124,23 +122,31 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
    *       consideration cannot be referenced directly.)
    * </ul>
    */
-  private static Optional<String> findMethodRenameBlocker(String methodName, VisitorState state) {
-    if (MoreASTHelpers.methodExistsInEnclosingClass(methodName, state)) {
+  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` already exists in this class", methodName));
+          String.format(
+              "a method named `%s` is already defined in this class or a supertype", newName));
     }
 
-    if (isSimpleNameStaticallyImported(methodName, state)) {
-      return Optional.of(String.format("`%s` is already statically imported", methodName));
+    if (isSimpleNameStaticallyImported(newName, state)) {
+      return Optional.of(String.format("`%s` is already statically imported", newName));
     }
 
-    if (isReservedKeyword(methodName)) {
-      return Optional.of(String.format("`%s` is a reserved keyword", methodName));
+    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)
@@ -154,12 +160,18 @@ public final class JUnitMethodDeclaration extends BugChecker implements MethodTr
     return source.subSequence(source.lastIndexOf('.') + 1, source.length());
   }
 
-  private static Optional<String> tryCanonicalizeMethodName(MethodTree tree) {
-    return Optional.of(ASTHelpers.getSymbol(tree).getQualifiedName().toString())
+  private static Optional<String> tryCanonicalizeMethodName(Symbol symbol) {
+    return Optional.of(symbol.getQualifiedName().toString())
         .filter(name -> name.startsWith(TEST_PREFIX))
         .map(name -> name.substring(TEST_PREFIX.length()))
         .filter(not(String::isEmpty))
         .map(name -> Character.toLowerCase(name.charAt(0)) + name.substring(1))
         .filter(name -> !Character.isDigit(name.charAt(0)));
   }
+
+  private static boolean isOverride(MethodTree tree, VisitorState state) {
+    return ASTHelpers.streamSuperMethods(ASTHelpers.getSymbol(tree), state.getTypes())
+        .findAny()
+        .isPresent();
+  }
 }

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

@@ -40,7 +40,7 @@ import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.AnnotationAttributeMatcher;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 

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

@@ -27,7 +27,7 @@ import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.TypeAnnotations.AnnotationType;
 import java.util.Comparator;
 import java.util.List;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**

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

@@ -41,8 +41,11 @@ public final class NestedOptionals extends BugChecker implements MethodInvocatio
 
   @Override
   public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
-    return state.getTypes().isSubtype(ASTHelpers.getType(tree), OPTIONAL_OF_OPTIONAL.get(state))
-        ? describeMatch(tree)
-        : Description.NO_MATCH;
+    Type type = OPTIONAL_OF_OPTIONAL.get(state);
+    if (type == null || !state.getTypes().isSubtype(ASTHelpers.getType(tree), type)) {
+      return Description.NO_MATCH;
+    }
+
+    return describeMatch(tree);
   }
 }

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

@@ -0,0 +1,90 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
+import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.suppliers.Supplier;
+import com.google.errorprone.suppliers.Suppliers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.code.Type;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import reactor.core.publisher.Flux;
+import reactor.test.StepVerifier;
+
+/**
+ * A {@link BugChecker} that flags duplicated usages of {@link StepVerifier.Step#expectNext} in
+ * favor of the overloaded variant.
+ *
+ * <p>{@link Flux#flatMap(Function)} and {@link Flux#flatMapSequential(Function)} eagerly perform up
+ * to {@link reactor.util.concurrent.Queues#SMALL_BUFFER_SIZE} subscriptions. Additionally, the
+ * former interleaves values as they are emitted, yielding nondeterministic results. In most cases
+ * {@link Flux#concatMap(Function)} should be preferred, as it produces consistent results and
+ * avoids potentially saturating the thread pool on which subscription happens. If {@code
+ * concatMap}'s sequential-subscription semantics are undesirable one should invoke a {@code
+ * flatMap} or {@code flatMapSequential} overload with an explicit concurrency level.
+ *
+ * <p>NB: The rarely-used overload {@link Flux#flatMap(Function, Function,
+ * java.util.function.Supplier)} is not flagged by this check because there is no clear alternative
+ * to point to.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary =
+        "When chaining multiple `StepVerifier.Step#expectNext` calls, please use the varargs overload instead",
+    link = BUG_PATTERNS_BASE_URL + "StepVerifierDuplicateExpectNext",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class StepVerifierDuplicateExpectNext extends BugChecker
+    implements MethodInvocationTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Supplier<Type> STEP =
+      Suppliers.typeFromString("reactor.test.StepVerifier.Step");
+  private static final Matcher<ExpressionTree> STEP_EXPECTNEXT =
+      instanceMethod().onDescendantOf(STEP).named("expectNext");
+
+  /** Instantiates a new {@link StepVerifierDuplicateExpectNext} instance. */
+  public StepVerifierDuplicateExpectNext() {}
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    if (!STEP_EXPECTNEXT.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+
+    MemberSelectTree ms = (MemberSelectTree) tree.getMethodSelect();
+    MethodInvocationTree parent = (MethodInvocationTree) (ms).getExpression();
+    boolean matches = STEP_EXPECTNEXT.matches(parent, state);
+    if (!matches) {
+      return Description.NO_MATCH;
+    }
+
+    List<? extends ExpressionTree> args = parent.getArguments();
+    String newArgument =
+        tree.getArguments().stream().map(Object::toString).collect(Collectors.joining(", "));
+    SuggestedFix.Builder argumentsFix =
+        SuggestedFix.builder().postfixWith(args.get(args.size() - 1), ", " + newArgument);
+    int startPosition = state.getEndPosition(parent);
+    int endPosition = state.getEndPosition(tree);
+
+    SuggestedFix removeDuplicateCall = SuggestedFix.replace(startPosition, endPosition, "");
+    Description.Builder description = buildDescription(tree);
+    description.addFix(argumentsFix.merge(removeDuplicateCall).build());
+    return description.build();
+  }
+}

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

@@ -4,9 +4,11 @@ import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
 import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.FRAGILE_CODE;
 import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
+import static com.sun.tools.javac.parser.Tokens.TokenKind.RPAREN;
 import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
+import com.google.common.collect.Streams;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -15,8 +17,11 @@ import com.google.errorprone.fixes.Fix;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.matchers.Description;
 import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.google.errorprone.util.ErrorProneTokens;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
+import com.sun.tools.javac.util.Position;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**
@@ -51,20 +56,34 @@ public final class StringCaseLocaleUsage extends BugChecker implements MethodInv
       return Description.NO_MATCH;
     }
 
+    int closingParenPosition = getClosingParenPosition(tree, state);
+    if (closingParenPosition == Position.NOPOS) {
+      return describeMatch(tree);
+    }
+
     return buildDescription(tree)
-        .addFix(suggestLocale(tree, "Locale.ROOT", state))
-        .addFix(suggestLocale(tree, "Locale.getDefault()", state))
+        .addFix(suggestLocale(closingParenPosition, "Locale.ROOT"))
+        .addFix(suggestLocale(closingParenPosition, "Locale.getDefault()"))
         .build();
   }
 
-  private static Fix suggestLocale(MethodInvocationTree tree, String locale, VisitorState state) {
-    // XXX: The logic that replaces the first parenthesis assumes that `tree` does not have a source
-    // code representation such as `str.toLowerCase/* Some comment with parens (). */()`. In such a
-    // case the comment, rather than the method invocation arguments, will be modified. Implement a
-    // generic solution for this.
+  private static Fix suggestLocale(int insertPosition, String locale) {
     return SuggestedFix.builder()
         .addImport("java.util.Locale")
-        .replace(tree, SourceCode.treeToString(tree, state).replaceFirst("\\(", '(' + locale))
+        .replace(insertPosition, insertPosition, locale)
         .build();
   }
+
+  private static int getClosingParenPosition(MethodInvocationTree tree, VisitorState state) {
+    int startPosition = ASTHelpers.getStartPosition(tree);
+    if (startPosition == Position.NOPOS) {
+      return Position.NOPOS;
+    }
+
+    return Streams.findLast(
+            ErrorProneTokens.getTokens(SourceCode.treeToString(tree, state), state.context).stream()
+                .filter(t -> t.kind() == RPAREN))
+        .map(token -> startPosition + token.pos())
+        .orElse(Position.NOPOS);
+  }
 }

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

@@ -27,7 +27,7 @@ import com.sun.tools.javac.util.Convert;
 import java.util.Formattable;
 import java.util.Iterator;
 import java.util.List;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
 /**

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

@@ -1,4 +1,4 @@
 /** Picnic Error Prone Contrib checks. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.bugpatterns;

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

@@ -4,7 +4,19 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 
 /** Utility class that can be used to identify reserved keywords of the Java language. */
+// XXX: This class is no longer only about keywords. Consider changing its name and class-level
+// documentation.
 public final class JavaKeywords {
+  /**
+   * Enumeration of boolean and null literals.
+   *
+   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.10.3">JDK 17
+   *     JLS section 3.10.3: Boolean Literals</a>
+   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.10.8">JDK 17
+   *     JLS section 3.10.8: The Null Literal</a>
+   */
+  private static final ImmutableSet<String> BOOLEAN_AND_NULL_LITERALS =
+      ImmutableSet.of("true", "false", "null");
   /**
    * List of all reserved keywords in the Java language.
    *
@@ -64,7 +76,6 @@ public final class JavaKeywords {
           "void",
           "volatile",
           "while");
-
   /**
    * List of all contextual keywords in the Java language.
    *
@@ -89,13 +100,28 @@ public final class JavaKeywords {
           "var",
           "with",
           "yield");
-
   /** List of all keywords in the Java language. */
   private static final ImmutableSet<String> ALL_KEYWORDS =
       Sets.union(RESERVED_KEYWORDS, CONTEXTUAL_KEYWORDS).immutableCopy();
 
   private JavaKeywords() {}
 
+  /**
+   * Tells whether the given string is a valid identifier in the Java language.
+   *
+   * @param str The string of interest.
+   * @return {@code true} if the given string is a valid identifier in the Java language.
+   * @see <a href="https://docs.oracle.com/javase/specs/jls/se17/html/jls-3.html#jls-3.8">JDK 17 JLS
+   *     section 3.8: Identifiers</a>
+   */
+  public static boolean isValidIdentifier(String str) {
+    return !str.isEmpty()
+        && !isReservedKeyword(str)
+        && !BOOLEAN_AND_NULL_LITERALS.contains(str)
+        && Character.isJavaIdentifierStart(str.codePointAt(0))
+        && str.codePoints().skip(1).allMatch(Character::isUnicodeIdentifierPart);
+  }
+
   /**
    * Tells whether the given string is a reserved keyword in the Java language.
    *

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

@@ -18,7 +18,7 @@ import com.sun.source.tree.AnnotationTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodTree;
 import com.sun.source.tree.NewArrayTree;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A collection of JUnit-specific helper methods and {@link Matcher}s.

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

@@ -1,4 +1,4 @@
 /** Auxiliary utilities for use by Error Prone checks. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.bugpatterns.util;

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

@@ -24,7 +24,7 @@ import java.util.Iterator;
 import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Stream;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /**
@@ -103,7 +103,8 @@ final class AssortedRules {
     }
 
     @AfterTemplate
-    @Nullable T after(Iterator<T> iterator, T defaultValue) {
+    @Nullable
+    T after(Iterator<T> iterator, T defaultValue) {
       return Iterators.getNext(iterator, defaultValue);
     }
   }

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

@@ -141,6 +141,22 @@ final class DoubleStreamRules {
     }
   }
 
+  /**
+   * Apply {@link DoubleStream#filter(DoublePredicate)} before {@link DoubleStream#sorted()} to
+   * reduce the number of elements to sort.
+   */
+  static final class DoubleStreamFilterSorted {
+    @BeforeTemplate
+    DoubleStream before(DoubleStream stream, DoublePredicate predicate) {
+      return stream.sorted().filter(predicate);
+    }
+
+    @AfterTemplate
+    DoubleStream after(DoubleStream stream, DoublePredicate predicate) {
+      return stream.filter(predicate).sorted();
+    }
+  }
+
   /** In order to test whether a stream has any element, simply try to find one. */
   static final class DoubleStreamIsEmpty {
     @BeforeTemplate

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

@@ -154,6 +154,22 @@ final class IntStreamRules {
     }
   }
 
+  /**
+   * Apply {@link IntStream#filter(IntPredicate)} before {@link IntStream#sorted()} to reduce the
+   * number of elements to sort.
+   */
+  static final class IntStreamFilterSorted {
+    @BeforeTemplate
+    IntStream before(IntStream stream, IntPredicate predicate) {
+      return stream.sorted().filter(predicate);
+    }
+
+    @AfterTemplate
+    IntStream after(IntStream stream, IntPredicate predicate) {
+      return stream.filter(predicate).sorted();
+    }
+  }
+
   /** In order to test whether a stream has any element, simply try to find one. */
   static final class IntStreamIsEmpty {
     @BeforeTemplate

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

@@ -154,6 +154,22 @@ final class LongStreamRules {
     }
   }
 
+  /**
+   * Apply {@link LongStream#filter(LongPredicate)} before {@link LongStream#sorted()} to reduce the
+   * number of elements to sort.
+   */
+  static final class LongStreamFilterSorted {
+    @BeforeTemplate
+    LongStream before(LongStream stream, LongPredicate predicate) {
+      return stream.sorted().filter(predicate);
+    }
+
+    @AfterTemplate
+    LongStream after(LongStream stream, LongPredicate predicate) {
+      return stream.filter(predicate).sorted();
+    }
+  }
+
   /** In order to test whether a stream has any element, simply try to find one. */
   static final class LongStreamIsEmpty {
     @BeforeTemplate

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

@@ -7,7 +7,7 @@ import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.stream.Stream;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with {@link Map} instances. */
@@ -31,12 +31,14 @@ final class MapRules {
 
   static final class MapGetOrNull<K, V, T> {
     @BeforeTemplate
-    @Nullable V before(Map<K, V> map, T key) {
+    @Nullable
+    V before(Map<K, V> map, T key) {
       return map.getOrDefault(key, null);
     }
 
     @AfterTemplate
-    @Nullable V after(Map<K, V> map, T key) {
+    @Nullable
+    V after(Map<K, V> map, T key) {
       return map.get(key);
     }
   }

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

@@ -7,7 +7,7 @@ import com.google.errorprone.refaster.annotation.AfterTemplate;
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import java.util.Collection;
 import java.util.Set;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with {@link Multimap}s. */
@@ -50,7 +50,8 @@ final class MultimapRules {
    */
   static final class MultimapGet<K, V> {
     @BeforeTemplate
-    @Nullable Collection<V> before(Multimap<K, V> multimap, K key) {
+    @Nullable
+    Collection<V> before(Multimap<K, V> multimap, K key) {
       return Refaster.anyOf(multimap.asMap(), Multimaps.asMap(multimap)).get(key);
     }
 

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

@@ -9,7 +9,7 @@ import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Objects;
 import java.util.function.Predicate;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with (possibly) null values. */

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

@@ -16,7 +16,7 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with {@link Optional}s. */

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

@@ -17,6 +17,7 @@ import com.google.errorprone.refaster.annotation.NotMatches;
 import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.time.Duration;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Optional;
 import java.util.concurrent.Callable;
@@ -26,7 +27,7 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
@@ -364,13 +365,21 @@ final class ReactorRules {
     }
   }
 
-  /** Don't unnecessarily pass an empty publisher to {@link Mono#switchIfEmpty(Mono)}. */
-  static final class MonoSwitchIfEmptyOfEmptyPublisher<T> {
+  /** Don't unnecessarily transform a {@link Mono} to an equivalent instance. */
+  static final class MonoIdentity<T> {
     @BeforeTemplate
     Mono<T> before(Mono<T> mono) {
       return mono.switchIfEmpty(Mono.empty());
     }
 
+    // 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();
+    }
+
     @AfterTemplate
     Mono<T> after(Mono<T> mono) {
       return mono;
@@ -674,6 +683,19 @@ final class ReactorRules {
     }
   }
 
+  /** Prefer direct invocation of {@link Mono#then()}} over more contrived alternatives. */
+  static final class MonoThen<T> {
+    @BeforeTemplate
+    Mono<@Nullable Void> before(Mono<T> mono) {
+      return mono.flux().then();
+    }
+
+    @AfterTemplate
+    Mono<@Nullable Void> after(Mono<T> mono) {
+      return mono.then();
+    }
+  }
+
   /**
    * Prefer a collection using {@link MoreCollectors#toOptional()} over more contrived alternatives.
    */
@@ -1062,6 +1084,38 @@ final class ReactorRules {
     }
   }
 
+  /**
+   * Apply {@link Flux#filter(Predicate)} before {@link Flux#sort()} to reduce the number of
+   * elements to sort.
+   */
+  static final class FluxFilterSort<T> {
+    @BeforeTemplate
+    Flux<T> before(Flux<T> flux, Predicate<? super T> predicate) {
+      return flux.sort().filter(predicate);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Flux<T> flux, Predicate<? super T> predicate) {
+      return flux.filter(predicate).sort();
+    }
+  }
+
+  /**
+   * Apply {@link Flux#filter(Predicate)} before {@link Flux#sort(Comparator)} to reduce the number
+   * of elements to sort.
+   */
+  static final class FluxFilterSortWithComparator<T> {
+    @BeforeTemplate
+    Flux<T> before(Flux<T> flux, Predicate<? super T> predicate, Comparator<? super T> comparator) {
+      return flux.sort(comparator).filter(predicate);
+    }
+
+    @AfterTemplate
+    Flux<T> after(Flux<T> flux, Predicate<? super T> predicate, Comparator<? super T> comparator) {
+      return flux.filter(predicate).sort(comparator);
+    }
+  }
+
   /** Prefer {@link reactor.util.context.Context#empty()}} over more verbose alternatives. */
   // XXX: Consider introducing an `IsEmpty` matcher that identifies a wide range of guaranteed-empty
   // `Collection` and `Map` expressions.

error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/RxJava2AdapterRules.java

@@ -9,7 +9,7 @@ import io.reactivex.Flowable;
 import io.reactivex.Maybe;
 import io.reactivex.Observable;
 import io.reactivex.Single;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import reactor.adapter.rxjava.RxJava2Adapter;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;

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

@@ -167,6 +167,40 @@ final class StreamRules {
     }
   }
 
+  /**
+   * Apply {@link Stream#filter(Predicate)} before {@link Stream#sorted()} to reduce the number of
+   * elements to sort.
+   */
+  static final class StreamFilterSorted<T> {
+    @BeforeTemplate
+    Stream<T> before(Stream<T> stream, Predicate<? super T> predicate) {
+      return stream.sorted().filter(predicate);
+    }
+
+    @AfterTemplate
+    Stream<T> after(Stream<T> stream, Predicate<? super T> predicate) {
+      return stream.filter(predicate).sorted();
+    }
+  }
+
+  /**
+   * Apply {@link Stream#filter(Predicate)} before {@link Stream#sorted(Comparator)} to reduce the
+   * number of elements to sort.
+   */
+  static final class StreamFilterSortedWithComparator<T> {
+    @BeforeTemplate
+    Stream<T> before(
+        Stream<T> stream, Predicate<? super T> predicate, Comparator<? super T> comparator) {
+      return stream.sorted(comparator).filter(predicate);
+    }
+
+    @AfterTemplate
+    Stream<T> after(
+        Stream<T> stream, Predicate<? super T> predicate, Comparator<? super T> comparator) {
+      return stream.filter(predicate).sorted(comparator);
+    }
+  }
+
   /**
    * Where possible, clarify that a mapping operation will be applied only to a single stream
    * element.

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

@@ -16,7 +16,7 @@ import java.util.Collection;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Function;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
 
 /** Refaster rules related to expressions dealing with {@link String}s. */

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

@@ -1,4 +1,4 @@
 /** Picnic Refaster rules. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refasterrules;

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

@@ -16,7 +16,10 @@ final class IdentityConversionTest {
   void identification() {
     compilationTestHelper
         .addSourceLines(
-            "Foo.java",
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.instanceMethod;",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
+            "",
             "import com.google.common.collect.ImmutableBiMap;",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableListMultimap;",
@@ -28,12 +31,14 @@ final class IdentityConversionTest {
             "import com.google.common.collect.ImmutableSet;",
             "import com.google.common.collect.ImmutableSetMultimap;",
             "import com.google.common.collect.ImmutableTable;",
+            "import com.google.errorprone.matchers.Matcher;",
+            "import com.google.errorprone.matchers.Matchers;",
             "import reactor.adapter.rxjava.RxJava2Adapter;",
             "import reactor.core.publisher.Flux;",
             "import reactor.core.publisher.Mono;",
             "",
-            "public final class Foo {",
-            "  public void foo() {",
+            "public final class A {",
+            "  public void m() {",
             "    // BUG: Diagnostic contains:",
             "    Boolean b1 = Boolean.valueOf(Boolean.FALSE);",
             "    // BUG: Diagnostic contains:",
@@ -113,6 +118,13 @@ final class IdentityConversionTest {
             "    // BUG: Diagnostic contains:",
             "    short s4 = Short.valueOf(Short.MIN_VALUE);",
             "",
+            "    // BUG: Diagnostic contains:",
+            "    String boolStr = Boolean.valueOf(Boolean.FALSE).toString();",
+            "    int boolHash = Boolean.valueOf(false).hashCode();",
+            "    // BUG: Diagnostic contains:",
+            "    int byteHash = Byte.valueOf((Byte) Byte.MIN_VALUE).hashCode();",
+            "    String byteStr = Byte.valueOf(Byte.MIN_VALUE).toString();",
+            "",
             "    String str1 = String.valueOf(0);",
             "    // BUG: Diagnostic contains:",
             "    String str2 = String.valueOf(\"1\");",
@@ -143,7 +155,15 @@ final class IdentityConversionTest {
             "    ImmutableTable<Object, Object, Object> o11 = ImmutableTable.copyOf(ImmutableTable.of());",
             "",
             "    // BUG: Diagnostic contains:",
+            "    Matcher allOf1 = Matchers.allOf(instanceMethod());",
+            "    Matcher allOf2 = Matchers.allOf(instanceMethod(), staticMethod());",
+            "    // BUG: Diagnostic contains:",
+            "    Matcher anyOf1 = Matchers.anyOf(staticMethod());",
+            "    Matcher anyOf2 = Matchers.anyOf(instanceMethod(), staticMethod());",
+            "",
+            "    // BUG: Diagnostic contains:",
             "    Flux<Integer> flux1 = Flux.just(1).flatMap(e -> RxJava2Adapter.fluxToFlowable(Flux.just(2)));",
+            "",
             "    // BUG: Diagnostic contains:",
             "    Flux<Integer> flux2 = Flux.concat(Flux.just(1));",
             "    // BUG: Diagnostic contains:",
@@ -154,9 +174,9 @@ final class IdentityConversionTest {
             "    Flux<Integer> flux5 = Flux.merge(Flux.just(1));",
             "",
             "    // BUG: Diagnostic contains:",
-            "    Mono<Integer> m1 = Mono.from(Mono.just(1));",
+            "    Mono<Integer> mono1 = Mono.from(Mono.just(1));",
             "    // BUG: Diagnostic contains:",
-            "    Mono<Integer> m2 = Mono.fromDirect(Mono.just(1));",
+            "    Mono<Integer> mono2 = Mono.fromDirect(Mono.just(1));",
             "  }",
             "}")
         .doTest();
@@ -167,12 +187,15 @@ final class IdentityConversionTest {
     refactoringTestHelper
         .setFixChooser(FixChoosers.FIRST)
         .addInputLines(
-            "Foo.java",
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
             "import static org.mockito.Mockito.when;",
             "",
             "import com.google.common.collect.ImmutableCollection;",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableSet;",
+            "import com.google.errorprone.matchers.Matcher;",
+            "import com.google.errorprone.matchers.Matchers;",
             "import java.util.ArrayList;",
             "import java.util.Collection;",
             "import org.reactivestreams.Publisher;",
@@ -180,8 +203,8 @@ final class IdentityConversionTest {
             "import reactor.core.publisher.Flux;",
             "import reactor.core.publisher.Mono;",
             "",
-            "public final class Foo {",
-            "  public void foo() {",
+            "public final class A {",
+            "  public void m() {",
             "    ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());",
             "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",
             "",
@@ -206,18 +229,23 @@ final class IdentityConversionTest {
             "    Object o1 = ImmutableSet.copyOf(ImmutableList.of());",
             "    Object o2 = ImmutableSet.copyOf(ImmutableSet.of());",
             "",
+            "    Matcher matcher = Matchers.allOf(staticMethod());",
+            "",
             "    when(\"foo\".contains(\"f\")).thenAnswer(inv -> ImmutableSet.copyOf(ImmutableList.of(1)));",
             "  }",
             "",
             "  void bar(Publisher<Integer> publisher) {}",
             "}")
         .addOutputLines(
-            "Foo.java",
+            "A.java",
+            "import static com.google.errorprone.matchers.Matchers.staticMethod;",
             "import static org.mockito.Mockito.when;",
             "",
             "import com.google.common.collect.ImmutableCollection;",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableSet;",
+            "import com.google.errorprone.matchers.Matcher;",
+            "import com.google.errorprone.matchers.Matchers;",
             "import java.util.ArrayList;",
             "import java.util.Collection;",
             "import org.reactivestreams.Publisher;",
@@ -225,8 +253,8 @@ final class IdentityConversionTest {
             "import reactor.core.publisher.Flux;",
             "import reactor.core.publisher.Mono;",
             "",
-            "public final class Foo {",
-            "  public void foo() {",
+            "public final class A {",
+            "  public void m() {",
             "    ImmutableSet<Object> set1 = ImmutableSet.of();",
             "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",
             "",
@@ -251,6 +279,8 @@ final class IdentityConversionTest {
             "    Object o1 = ImmutableSet.copyOf(ImmutableList.of());",
             "    Object o2 = ImmutableSet.of();",
             "",
+            "    Matcher matcher = staticMethod();",
+            "",
             "    when(\"foo\".contains(\"f\")).thenAnswer(inv -> ImmutableSet.copyOf(ImmutableList.of(1)));",
             "  }",
             "",
@@ -264,14 +294,14 @@ final class IdentityConversionTest {
     refactoringTestHelper
         .setFixChooser(FixChoosers.SECOND)
         .addInputLines(
-            "Foo.java",
+            "A.java",
             "import com.google.common.collect.ImmutableCollection;",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableSet;",
             "import java.util.ArrayList;",
             "",
-            "public final class Foo {",
-            "  public void foo() {",
+            "public final class A {",
+            "  public void m() {",
             "    ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());",
             "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",
             "",
@@ -280,14 +310,14 @@ final class IdentityConversionTest {
             "  }",
             "}")
         .addOutputLines(
-            "Foo.java",
+            "A.java",
             "import com.google.common.collect.ImmutableCollection;",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableSet;",
             "import java.util.ArrayList;",
             "",
-            "public final class Foo {",
-            "  public void foo() {",
+            "public final class A {",
+            "  public void m() {",
             "    @SuppressWarnings(\"IdentityConversion\")",
             "    ImmutableSet<Object> set1 = ImmutableSet.copyOf(ImmutableSet.of());",
             "    ImmutableSet<Object> set2 = ImmutableSet.copyOf(ImmutableList.of());",

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

@@ -17,12 +17,28 @@ final class IsInstanceLambdaUsageTest {
         .addSourceLines(
             "A.java",
             "import java.util.stream.Stream;",
+            "import reactor.core.publisher.Flux;",
             "",
             "class A {",
             "  void m() {",
+            "    Integer localVariable = 0;",
+            "",
+            "    Stream.of(0).map(i -> i + 1);",
+            "    Stream.of(1).filter(Integer.class::isInstance);",
+            "    Stream.of(2).filter(i -> i.getClass() instanceof Class);",
+            "    Stream.of(3).filter(i -> localVariable instanceof Integer);",
+            "    // XXX: Ideally this case is also flagged. Pick this up in the context of merging the",
+            "    // `IsInstanceLambdaUsage` and `MethodReferenceUsage` checks, or introduce a separate check that",
+            "    // simplifies unnecessary block lambda expressions.",
+            "    Stream.of(4)",
+            "        .filter(",
+            "            i -> {",
+            "              return localVariable instanceof Integer;",
+            "            });",
+            "    Flux.just(5, \"foo\").distinctUntilChanged(v -> v, (a, b) -> a instanceof Integer);",
+            "",
             "    // BUG: Diagnostic contains:",
-            "    Stream.of(1).filter(i -> i instanceof Integer);",
-            "    Stream.of(2).filter(Integer.class::isInstance);",
+            "    Stream.of(6).filter(i -> i instanceof Integer);",
             "  }",
             "}")
         .doTest();

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

@@ -91,6 +91,9 @@ final class JUnitMethodDeclarationTest {
             "  private void tearDown8() {}",
             "",
             "  @Test",
+            "  void test() {}",
+            "",
+            "  @Test",
             "  void method1() {}",
             "",
             "  @Test",
@@ -144,8 +147,13 @@ final class JUnitMethodDeclarationTest {
             "  void test5() {}",
             "",
             "  @Test",
-            "  // BUG: Diagnostic contains: (but note that a method named `overload` already exists in this",
-            "  // class)",
+            "  // BUG: Diagnostic contains: (but note that a method named `toString` is already defined in this",
+            "  // class or a supertype)",
+            "  void testToString() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains: (but note that a method named `overload` is already defined in this",
+            "  // class or a supertype)",
             "  void testOverload() {}",
             "",
             "  void overload() {}",
@@ -155,8 +163,20 @@ final class JUnitMethodDeclarationTest {
             "  void testArguments() {}",
             "",
             "  @Test",
-            "  // BUG: Diagnostic contains: (but note that `public` is a reserved keyword)",
+            "  // BUG: Diagnostic contains: (but note that `public` is not a valid identifier)",
             "  void testPublic() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains: (but note that `null` is not a valid identifier)",
+            "  void testNull() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains:",
+            "  void testRecord() {}",
+            "",
+            "  @Test",
+            "  // BUG: Diagnostic contains:",
+            "  void testMethodThatIsOverriddenWithoutOverrideAnnotation() {}",
             "}")
         .addSourceLines(
             "B.java",
@@ -218,6 +238,10 @@ final class JUnitMethodDeclarationTest {
             "",
             "  @Override",
             "  @Test",
+            "  void test() {}",
+            "",
+            "  @Override",
+            "  @Test",
             "  void method1() {}",
             "",
             "  @Override",
@@ -267,6 +291,10 @@ final class JUnitMethodDeclarationTest {
             "",
             "  @Override",
             "  @Test",
+            "  void testToString() {}",
+            "",
+            "  @Override",
+            "  @Test",
             "  void testOverload() {}",
             "",
             "  @Override",
@@ -279,6 +307,17 @@ final class JUnitMethodDeclarationTest {
             "  @Override",
             "  @Test",
             "  void testPublic() {}",
+            "",
+            "  @Override",
+            "  @Test",
+            "  void testNull() {}",
+            "",
+            "  @Override",
+            "  @Test",
+            "  void testRecord() {}",
+            "",
+            "  @Test",
+            "  void testMethodThatIsOverriddenWithoutOverrideAnnotation() {}",
             "}")
         .addSourceLines(
             "C.java",
@@ -352,6 +391,9 @@ final class JUnitMethodDeclarationTest {
             "  protected void quux() {}",
             "",
             "  @Test",
+            "  public void testToString() {}",
+            "",
+            "  @Test",
             "  public void testOverload() {}",
             "",
             "  void overload() {}",
@@ -361,6 +403,9 @@ final class JUnitMethodDeclarationTest {
             "",
             "  @Test",
             "  private void testClass() {}",
+            "",
+            "  @Test",
+            "  private void testTrue() {}",
             "}")
         .addOutputLines(
             "A.java",
@@ -407,6 +452,9 @@ final class JUnitMethodDeclarationTest {
             "  void quux() {}",
             "",
             "  @Test",
+            "  void testToString() {}",
+            "",
+            "  @Test",
             "  void testOverload() {}",
             "",
             "  void overload() {}",
@@ -416,6 +464,9 @@ final class JUnitMethodDeclarationTest {
             "",
             "  @Test",
             "  void testClass() {}",
+            "",
+            "  @Test",
+            "  void testTrue() {}",
             "}")
         .doTest(TestMode.TEXT_MATCH);
   }

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

@@ -39,4 +39,19 @@ final class NestedOptionalsTest {
             "}")
         .doTest();
   }
+
+  @Test
+  void identificationOptionalTypeNotLoaded() {
+    compilationTestHelper
+        .addSourceLines(
+            "A.java",
+            "import java.time.Duration;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Duration.ofSeconds(1);",
+            "  }",
+            "}")
+        .doTest();
+  }
 }

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

@@ -19,7 +19,7 @@ final class RequestParamTypeTest {
             "import java.util.List;",
             "import java.util.Map;",
             "import java.util.Set;",
-            "import org.jspecify.nullness.Nullable;",
+            "import org.jspecify.annotations.Nullable;",
             "import org.springframework.web.bind.annotation.DeleteMapping;",
             "import org.springframework.web.bind.annotation.GetMapping;",
             "import org.springframework.web.bind.annotation.PostMapping;",

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

@@ -0,0 +1,68 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugCheckerRefactoringTestHelper.newInstance;
+
+import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+public class StepVerifierDuplicateExpectNextTest {
+  private final CompilationTestHelper compilationTestHelper =
+      CompilationTestHelper.newInstance(StepVerifierDuplicateExpectNext.class, getClass());
+  private final BugCheckerRefactoringTestHelper refactoringTestHelper =
+      newInstance(StepVerifierDuplicateExpectNext.class, getClass());
+
+  @Test
+  void replacementFirstSuggestedFix() {
+    refactoringTestHelper
+        .addInputLines(
+            "A.java",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.test.StepVerifier;",
+            "",
+            "class A {",
+            "  void m() {",
+            "     // BUG Diagnotics contains:",
+            "     Flux.just(0, 1).as(StepVerifier::create).expectNext(0).expectNext(1);",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.test.StepVerifier;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(0, 1).as(StepVerifier::create).expectNext(0, 1);",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+
+  @Test
+  void replacement2() {
+    refactoringTestHelper
+        .addInputLines(
+            "A.java",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.test.StepVerifier;",
+            "",
+            "class A {",
+            "  void m() {",
+            "     Flux.just(0, 1).as(StepVerifier::create).expectNext(0).expectNext(1).verifyComplete();",
+            "  }",
+            "}")
+        .addOutputLines(
+            "A.java",
+            "import reactor.core.publisher.Flux;",
+            "import reactor.test.StepVerifier;",
+            "",
+            "class A {",
+            "  void m() {",
+            "    Flux.just(0, 1).as(StepVerifier::create).expectNext(0, 1).verifyComplete();",
+            "  }",
+            "}")
+        .doTest(TestMode.TEXT_MATCH);
+  }
+}

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

@@ -62,6 +62,13 @@ final class StringCaseLocaleUsageTest {
             "  void m() {",
             "    \"a\".toLowerCase(/* Comment with parens: (). */ );",
             "    \"b\".toUpperCase();",
+            "    \"c\".toLowerCase().toString();",
+            "",
+            "    toString().toLowerCase();",
+            "    toString().toUpperCase /* Comment with parens: (). */();",
+            "",
+            "    this.toString().toLowerCase() /* Comment with parens: (). */;",
+            "    this.toString().toUpperCase();",
             "  }",
             "}")
         .addOutputLines(
@@ -70,8 +77,15 @@ final class StringCaseLocaleUsageTest {
             "",
             "class A {",
             "  void m() {",
-            "    \"a\".toLowerCase(Locale.ROOT /* Comment with parens: (). */);",
+            "    \"a\".toLowerCase(/* Comment with parens: (). */ Locale.ROOT);",
             "    \"b\".toUpperCase(Locale.ROOT);",
+            "    \"c\".toLowerCase(Locale.ROOT).toString();",
+            "",
+            "    toString().toLowerCase(Locale.ROOT);",
+            "    toString().toUpperCase /* Comment with parens: (). */(Locale.ROOT);",
+            "",
+            "    this.toString().toLowerCase(Locale.ROOT) /* Comment with parens: (). */;",
+            "    this.toString().toUpperCase(Locale.ROOT);",
             "  }",
             "}")
         .doTest(TestMode.TEXT_MATCH);
@@ -87,6 +101,13 @@ final class StringCaseLocaleUsageTest {
             "  void m() {",
             "    \"a\".toLowerCase();",
             "    \"b\".toUpperCase(/* Comment with parens: (). */ );",
+            "    \"c\".toLowerCase().toString();",
+            "",
+            "    toString().toLowerCase();",
+            "    toString().toUpperCase /* Comment with parens: (). */();",
+            "",
+            "    this.toString().toLowerCase() /* Comment with parens: (). */;",
+            "    this.toString().toUpperCase();",
             "  }",
             "}")
         .addOutputLines(
@@ -96,7 +117,14 @@ final class StringCaseLocaleUsageTest {
             "class A {",
             "  void m() {",
             "    \"a\".toLowerCase(Locale.getDefault());",
-            "    \"b\".toUpperCase(Locale.getDefault() /* Comment with parens: (). */);",
+            "    \"b\".toUpperCase(/* Comment with parens: (). */ Locale.getDefault());",
+            "    \"c\".toLowerCase(Locale.getDefault()).toString();",
+            "",
+            "    toString().toLowerCase(Locale.getDefault());",
+            "    toString().toUpperCase /* Comment with parens: (). */(Locale.getDefault());",
+            "",
+            "    this.toString().toLowerCase(Locale.getDefault()) /* Comment with parens: (). */;",
+            "    this.toString().toUpperCase(Locale.getDefault());",
             "  }",
             "}")
         .doTest(TestMode.TEXT_MATCH);

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

@@ -0,0 +1,34 @@
+package tech.picnic.errorprone.bugpatterns.util;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+
+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 JavaKeywordsTest {
+  private static Stream<Arguments> isValidIdentifierTestCases() {
+    /* { str, expected } */
+    return Stream.of(
+        arguments("", false),
+        arguments("public", false),
+        arguments("true", false),
+        arguments("false", false),
+        arguments("null", false),
+        arguments("0", false),
+        arguments("\0", false),
+        arguments("a%\0", false),
+        arguments("a", true),
+        arguments("a0", true),
+        arguments("_a0", true),
+        arguments("test", true));
+  }
+
+  @MethodSource("isValidIdentifierTestCases")
+  @ParameterizedTest
+  void isValidIdentifier(String str, boolean expected) {
+    assertThat(JavaKeywords.isValidIdentifier(str)).isEqualTo(expected);
+  }
+}

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

@@ -46,6 +46,10 @@ final class DoubleStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToDouble(v -> DoubleStream.of(v * v).flatMap(DoubleStream::of));
   }
 
+  DoubleStream testDoubleStreamFilterSorted() {
+    return DoubleStream.of(1, 4, 3, 2).sorted().filter(d -> d % 2 == 0);
+  }
+
   ImmutableSet<Boolean> testDoubleStreamIsEmpty() {
     return ImmutableSet.of(
         DoubleStream.of(1).count() == 0,

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

@@ -46,6 +46,10 @@ final class DoubleStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToDouble(v -> DoubleStream.of(v * v)).flatMap(DoubleStream::of);
   }
 
+  DoubleStream testDoubleStreamFilterSorted() {
+    return DoubleStream.of(1, 4, 3, 2).filter(d -> d % 2 == 0).sorted();
+  }
+
   ImmutableSet<Boolean> testDoubleStreamIsEmpty() {
     return ImmutableSet.of(
         DoubleStream.of(1).findAny().isEmpty(),

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

@@ -50,6 +50,10 @@ final class IntStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToInt(v -> IntStream.of(v * v).flatMap(IntStream::of));
   }
 
+  IntStream testIntStreamFilterSorted() {
+    return IntStream.of(1, 4, 3, 2).sorted().filter(i -> i % 2 == 0);
+  }
+
   ImmutableSet<Boolean> testIntStreamIsEmpty() {
     return ImmutableSet.of(
         IntStream.of(1).count() == 0,

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

@@ -50,6 +50,10 @@ final class IntStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToInt(v -> IntStream.of(v * v)).flatMap(IntStream::of);
   }
 
+  IntStream testIntStreamFilterSorted() {
+    return IntStream.of(1, 4, 3, 2).filter(i -> i % 2 == 0).sorted();
+  }
+
   ImmutableSet<Boolean> testIntStreamIsEmpty() {
     return ImmutableSet.of(
         IntStream.of(1).findAny().isEmpty(),

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

@@ -50,6 +50,10 @@ final class LongStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToLong(v -> LongStream.of(v * v).flatMap(LongStream::of));
   }
 
+  LongStream testLongStreamFilterSorted() {
+    return LongStream.of(1, 4, 3, 2).sorted().filter(l -> l % 2 == 0);
+  }
+
   ImmutableSet<Boolean> testLongStreamIsEmpty() {
     return ImmutableSet.of(
         LongStream.of(1).count() == 0,

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

@@ -50,6 +50,10 @@ final class LongStreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of(1).flatMapToLong(v -> LongStream.of(v * v)).flatMap(LongStream::of);
   }
 
+  LongStream testLongStreamFilterSorted() {
+    return LongStream.of(1, 4, 3, 2).filter(l -> l % 2 == 0).sorted();
+  }
+
   ImmutableSet<Boolean> testLongStreamIsEmpty() {
     return ImmutableSet.of(
         LongStream.of(1).findAny().isEmpty(),

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

@@ -1,5 +1,6 @@
 package tech.picnic.errorprone.refasterrules;
 
+import static java.util.Comparator.reverseOrder;
 import static java.util.function.Function.identity;
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -114,8 +115,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just("baz").switchIfEmpty(Flux.just("qux")));
   }
 
-  Mono<Integer> testMonoSwitchIfEmptyOfEmptyPublisher() {
-    return Mono.just(1).switchIfEmpty(Mono.empty());
+  ImmutableSet<Mono<?>> testMonoIdentity() {
+    return ImmutableSet.of(Mono.just(1).switchIfEmpty(Mono.empty()), Mono.<Void>empty().then());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {
@@ -220,6 +221,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.concat(Mono.just("baz")));
   }
 
+  Mono<Void> testMonoThen() {
+    return Mono.just("foo").flux().then();
+  }
+
   Mono<Optional<String>> testMonoCollectToOptional() {
     return Mono.just("foo").map(Optional::of).defaultIfEmpty(Optional.empty());
   }
@@ -327,6 +332,14 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
     return Flux.just(1).onErrorReturn(IllegalArgumentException.class::isInstance, 2);
   }
 
+  Flux<Integer> testFluxFilterSort() {
+    return Flux.just(1, 4, 3, 2).sort().filter(i -> i % 2 == 0);
+  }
+
+  Flux<Integer> testFluxFilterSortWithComparator() {
+    return Flux.just(1, 4, 3, 2).sort(reverseOrder()).filter(i -> i % 2 == 0);
+  }
+
   ImmutableSet<Context> testContextEmpty() {
     return ImmutableSet.of(Context.of(new HashMap<>()), Context.of(ImmutableMap.of()));
   }

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

@@ -1,6 +1,7 @@
 package tech.picnic.errorprone.refasterrules;
 
 import static com.google.common.collect.MoreCollectors.toOptional;
+import static java.util.Comparator.reverseOrder;
 import static java.util.function.Function.identity;
 import static org.assertj.core.api.Assertions.assertThat;
 import static reactor.function.TupleUtils.function;
@@ -119,8 +120,8 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Flux.just("foo").defaultIfEmpty("bar"), Flux.just("baz").defaultIfEmpty("qux"));
   }
 
-  Mono<Integer> testMonoSwitchIfEmptyOfEmptyPublisher() {
-    return Mono.just(1);
+  ImmutableSet<Mono<?>> testMonoIdentity() {
+    return ImmutableSet.of(Mono.just(1), Mono.<Void>empty());
   }
 
   ImmutableSet<Flux<Integer>> testFluxSwitchIfEmptyOfEmptyPublisher() {
@@ -219,6 +220,10 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
         Mono.just("foo").flux(), Mono.just("bar").flux(), Mono.just("baz").flux());
   }
 
+  Mono<Void> testMonoThen() {
+    return Mono.just("foo").then();
+  }
+
   Mono<Optional<String>> testMonoCollectToOptional() {
     return Mono.just("foo").flux().collect(toOptional());
   }
@@ -322,6 +327,14 @@ final class ReactorRulesTest implements RefasterRuleCollectionTestCase {
     return Flux.just(1).onErrorReturn(IllegalArgumentException.class, 2);
   }
 
+  Flux<Integer> testFluxFilterSort() {
+    return Flux.just(1, 4, 3, 2).filter(i -> i % 2 == 0).sort();
+  }
+
+  Flux<Integer> testFluxFilterSortWithComparator() {
+    return Flux.just(1, 4, 3, 2).filter(i -> i % 2 == 0).sort(reverseOrder());
+  }
+
   ImmutableSet<Context> testContextEmpty() {
     return ImmutableSet.of(Context.empty(), Context.empty());
   }

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

@@ -16,7 +16,7 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class StreamRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Objects.class, Streams.class, not(null), reverseOrder());
+    return ImmutableSet.of(Objects.class, Streams.class, not(null));
   }
 
   String testJoining() {
@@ -56,6 +56,14 @@ final class StreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of("foo").flatMap(v -> Stream.of(v.length()).flatMap(Stream::of));
   }
 
+  Stream<Integer> testStreamFilterSorted() {
+    return Stream.of(1, 4, 3, 2).sorted().filter(i -> i % 2 == 0);
+  }
+
+  Stream<Integer> testStreamFilterSortedWithComparator() {
+    return Stream.of(1, 4, 3, 2).sorted(reverseOrder()).filter(i -> i % 2 == 0);
+  }
+
   ImmutableSet<Optional<Integer>> testStreamMapFirst() {
     return ImmutableSet.of(
         Stream.of("foo").map(s -> s.length()).findFirst(),

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

@@ -18,7 +18,7 @@ import tech.picnic.errorprone.refaster.test.RefasterRuleCollectionTestCase;
 final class StreamRulesTest implements RefasterRuleCollectionTestCase {
   @Override
   public ImmutableSet<?> elidedTypesAndStaticImports() {
-    return ImmutableSet.of(Objects.class, Streams.class, not(null), reverseOrder());
+    return ImmutableSet.of(Objects.class, Streams.class, not(null));
   }
 
   String testJoining() {
@@ -57,6 +57,14 @@ final class StreamRulesTest implements RefasterRuleCollectionTestCase {
     return Stream.of("foo").flatMap(v -> Stream.of(v.length())).flatMap(Stream::of);
   }
 
+  Stream<Integer> testStreamFilterSorted() {
+    return Stream.of(1, 4, 3, 2).filter(i -> i % 2 == 0).sorted();
+  }
+
+  Stream<Integer> testStreamFilterSortedWithComparator() {
+    return Stream.of(1, 4, 3, 2).filter(i -> i % 2 == 0).sorted(reverseOrder());
+  }
+
   ImmutableSet<Optional<Integer>> testStreamMapFirst() {
     return ImmutableSet.of(
         Stream.of("foo").findFirst().map(s -> s.length()),

pom.xml

@@ -4,7 +4,7 @@
 
     <groupId>tech.picnic.error-prone-support</groupId>
     <artifactId>error-prone-support</artifactId>
-    <version>0.5.1-SNAPSHOT</version>
+    <version>0.6.1-SNAPSHOT</version>
     <packaging>pom</packaging>
 
     <name>Picnic :: Error Prone Support</name>
@@ -148,13 +148,13 @@
         <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-1</version.error-prone-fork>
+        <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.guava-beta-checker>1.0</version.guava-beta-checker>
         <version.jdk>11</version.jdk>
         <version.maven>3.8.6</version.maven>
-        <version.mockito>4.9.0</version.mockito>
+        <version.mockito>4.11.0</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>
@@ -281,7 +281,7 @@
             <dependency>
                 <groupId>io.projectreactor</groupId>
                 <artifactId>reactor-bom</artifactId>
-                <version>2022.0.0</version>
+                <version>2022.0.1</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -333,7 +333,7 @@
             <dependency>
                 <groupId>org.aspectj</groupId>
                 <artifactId>aspectjweaver</artifactId>
-                <version>1.9.9.1</version>
+                <version>1.9.19</version>
             </dependency>
             <dependency>
                 <groupId>org.assertj</groupId>
@@ -353,12 +353,12 @@
             <dependency>
                 <groupId>org.immutables</groupId>
                 <artifactId>value-annotations</artifactId>
-                <version>2.9.2</version>
+                <version>2.9.3</version>
             </dependency>
             <dependency>
                 <groupId>org.jspecify</groupId>
                 <artifactId>jspecify</artifactId>
-                <version>0.2.0</version>
+                <version>0.3.0</version>
             </dependency>
             <dependency>
                 <groupId>org.junit</groupId>
@@ -377,7 +377,7 @@
             <dependency>
                 <groupId>org.slf4j</groupId>
                 <artifactId>slf4j-api</artifactId>
-                <version>2.0.5</version>
+                <version>2.0.6</version>
             </dependency>
             <dependency>
                 <groupId>org.springframework</groupId>
@@ -389,7 +389,7 @@
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-test</artifactId>
-                <version>2.7.6</version>
+                <version>2.7.7</version>
             </dependency>
             <dependency>
                 <groupId>org.testng</groupId>
@@ -611,15 +611,15 @@
                                         </property>
                                         <property name="illegalClasses" value="com.mongodb.lang.Nullable">
                                             <!-- Instead, please use
-                                            `org.jspecify.nullness.Nullable`. -->
+                                            `org.jspecify.annotations.Nullable`. -->
                                         </property>
                                         <property name="illegalClasses" value="io.micrometer.core.lang.Nullable">
                                             <!-- Instead, please use
-                                            `org.jspecify.nullness.Nullable`. -->
+                                            `org.jspecify.annotations.Nullable`. -->
                                         </property>
                                         <property name="illegalClasses" value="javax.annotation.Nullable">
                                             <!-- Instead, please use
-                                            `org.jspecify.nullness.Nullable`. -->
+                                            `org.jspecify.annotations.Nullable`. -->
                                         </property>
                                         <property name="illegalClasses" value="javax.annotation.concurrent.Immutable">
                                             <!-- Instead, please use
@@ -635,7 +635,7 @@
                                         </property>
                                         <property name="illegalClasses" value="org.springframework.lang.Nullable">
                                             <!-- Instead, please use
-                                            `org.jspecify.nullness.Nullable`. -->
+                                            `org.jspecify.annotations.Nullable`. -->
                                         </property>
                                         <property name="illegalPkgs" value="com.amazonaws.annotation" />
                                         <property name="illegalPkgs" value="com.beust.jcommander.internal" />
@@ -852,6 +852,7 @@
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.api=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>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED</arg>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED</arg>
                             <arg>-Xmaxerrs</arg>
@@ -997,6 +998,7 @@
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</additionalJOption>
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED</additionalJOption>
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</additionalJOption>
+                            <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED</additionalJOption>
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED</additionalJOption>
                             <additionalJOption>--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED</additionalJOption>
                         </additionalJOptions>
@@ -1195,7 +1197,7 @@
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>versions-maven-plugin</artifactId>
-                    <version>2.13.0</version>
+                    <version>2.14.2</version>
                     <configuration>
                         <updateBuildOutputTimestampPolicy>never</updateBuildOutputTimestampPolicy>
                     </configuration>
@@ -1268,7 +1270,7 @@
                         <dependency>
                             <groupId>com.groupcdg.arcmutate</groupId>
                             <artifactId>base</artifactId>
-                            <version>1.0.1</version>
+                            <version>1.0.2</version>
                         </dependency>
                         <dependency>
                             <groupId>com.groupcdg.pitest</groupId>

refaster-compiler/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.5.1-SNAPSHOT</version>
+        <version>0.6.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-compiler</artifactId>

refaster-compiler/src/main/java/tech/picnic/errorprone/refaster/plugin/RefasterRuleCompilerTaskListener.java

@@ -31,7 +31,7 @@ import java.util.Map;
 import javax.tools.FileObject;
 import javax.tools.JavaFileManager;
 import javax.tools.StandardLocation;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.AnnotatedCompositeCodeTransformer;
 
 /**

refaster-compiler/src/main/java/tech/picnic/errorprone/refaster/plugin/package-info.java

@@ -3,5 +3,5 @@
  * files on the classpath.
  */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster.plugin;

refaster-runner/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.5.1-SNAPSHOT</version>
+        <version>0.6.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-runner</artifactId>

refaster-runner/src/main/java/tech/picnic/errorprone/refaster/runner/package-info.java

@@ -1,4 +1,4 @@
 /** Exposes Refaster rules found on the classpath through a regular Error Prone check. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster.runner;

refaster-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.5.1-SNAPSHOT</version>
+        <version>0.6.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-support</artifactId>

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

@@ -4,5 +4,5 @@
  * non-patch mode.
  */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster.annotation;

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

@@ -5,5 +5,5 @@
  * com.google.errorprone.refaster.annotation.NotMatches @NotMatches} annotations.
  */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster.matchers;

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

@@ -1,4 +1,4 @@
 /** Assorted classes that aid the compilation or evaluation of Refaster rules. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster;

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

@@ -11,7 +11,7 @@ import com.sun.source.tree.ImportTree;
 import com.sun.source.tree.MethodTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.util.TreeScanner;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * An abstract {@link BugChecker} that reports a match for each expression matched by the given

refaster-test-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.5.1-SNAPSHOT</version>
+        <version>0.6.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-test-support</artifactId>

refaster-test-support/src/main/java/tech/picnic/errorprone/refaster/test/RefasterRuleCollection.java

@@ -44,7 +44,7 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.regex.Pattern;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.refaster.runner.CodeTransformers;
 import tech.picnic.errorprone.refaster.runner.Refaster;
 

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

@@ -1,4 +1,4 @@
 /** Opinionated utilities for the testing of Refaster rules. */
 @com.google.errorprone.annotations.CheckReturnValue
-@org.jspecify.nullness.NullMarked
+@org.jspecify.annotations.NullMarked
 package tech.picnic.errorprone.refaster.test;

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

@@ -8,7 +8,7 @@ import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.errorprone.refaster.annotation.Placeholder;
 import com.google.errorprone.refaster.annotation.UseImportPolicy;
 import java.util.Set;
-import org.jspecify.nullness.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /** Refaster rule collection to validate that having no violations works as expected. */
 final class ValidRules {

website/README.md

@@ -24,6 +24,9 @@ If you are not familiar with Jekyll, be sure to check out its
 [documentation][jekyll-docs]. It is recommended to follow the provided
 step-by-step tutorial.
 
+We use the [Just the Docs][just-the-docs] Jekyll theme, which also includes
+several configuration options.
+
 ###### Switch Ruby versions
 
 The required Ruby version is set in `.ruby-version`. To switch, you can use
@@ -56,5 +59,6 @@ Actions workflow any time a change is merged to `master`.
 [jekyll]: https://jekyllrb.com
 [jekyll-docs]: https://jekyllrb.com/docs
 [jekyll-docs-installation]: https://jekyllrb.com/docs/installation
+[just-the-docs]: https://just-the-docs.github.io/just-the-docs/
 [localhost-port-4000]: http://127.0.0.1:4000
 [rvm]: https://rvm.io

website/_config.yml

@@ -28,6 +28,12 @@ nav_external_links:
     url: https://github.com/PicnicSupermarket/error-prone-support
     hide_icon: false
 
+callouts:
+  summary:
+    color: blue
+  note:
+    color: grey-dk
+
 # SEO configuration.
 # See https://jekyll.github.io/jekyll-seo-tag/usage.
 social:

website/_includes/footer_custom.html

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

website/_includes/head_custom.html

@@ -4,15 +4,15 @@
 <link rel="icon" type="image/png" sizes="16x16" href="/assets/images/favicon-16x16.png">
 <link rel="manifest" href="/assets/images/site.webmanifest">
 <link rel="mask-icon" href="/assets/images/safari-pinned-tab.svg" color="#5bbad5">
-<link rel="shortcut icon" href="/favicon.ico">
 <meta name="msapplication-TileColor" content="#da532c">
 <meta name="msapplication-config" content="/assets/images/browserconfig.xml">
 <meta name="theme-color" content="#ffffff">
 
-<!-- XXX: The theme does not natively support both light and dark mode. Drop
-this section once https://github.com/just-the-docs/just-the-docs/issues/234 is
-resolved. -->
+<!-- Support light and dark mode, as it's not natively supported. See
+https://github.com/just-the-docs/just-the-docs/issues/234. -->
 <link rel="stylesheet" href="{{ '/assets/css/just-the-docs-eps-light.css' | relative_url }}"
-    media="(prefers-color-scheme: light)">
+      media="(prefers-color-scheme: light)">
 <link rel="stylesheet" href="{{ '/assets/css/just-the-docs-eps-dark.css' | relative_url }}"
-    media="(prefers-color-scheme: dark)">
+      media="(prefers-color-scheme: dark)">
+
+<meta name="google-site-verification" content="2GBzy2ufS8Rfqffu8T6iqng6dbDw9EKuykMisUZU3IQ"/>

website/_sass/color_schemes/_common.scss

@@ -1,5 +1,20 @@
-footer > img#logo {
+// Add support for external anchor icons.
+.external > svg {
+  width: 1rem;
+  vertical-align: text-bottom;
+}
+
+.label {
+  // Reduce spacing between labels and align with surrounding elements.
+  margin-left: 0 !important;
+}
+
+footer {
+  text-align: center;
+
+  img#logo {
     width: 2rem;
     margin: 0 auto;
     display: block;
+  }
 }

website/_sass/color_schemes/_variables.scss

@@ -1 +1,5 @@
+// Overrides for Just the Docs. See
+// https://github.com/just-the-docs/just-the-docs/blob/main/_sass/support/_variables.scss.
+
+// Grid system.
 $nav-width: 400px;

website/_sass/color_schemes/eps-dark.scss

@@ -1,3 +1,16 @@
 @import "./color_schemes/dark";
 @import "_variables";
 @import "_common";
+
+// Swap `$blue-000` and `$blue-300`, mainly for callouts. This is done by
+// default for red, but not for other colors.
+$blue-000: #183385;
+$blue-300: #2c84fa;
+
+// Use light-theme greys in dark theme so that summary callouts stand out more.
+// (Note that the former has four shades, while the latter has five.)
+$grey-dk-000: $grey-lt-000;
+$grey-dk-100: $grey-lt-100;
+$grey-dk-200: $grey-lt-200;
+$grey-dk-250: $grey-lt-200;
+$grey-dk-300: $grey-lt-300;