Merge branch 'master' into sschroevers/refaster-speed-up

Since PIT correctly flags these as "redundant".

Also for JDK 11 compatibility.

.github/workflows/build.yml

@@ -26,7 +26,7 @@ jobs:
     continue-on-error: ${{ matrix.experimental }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/codeql.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/deploy-website.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block
@@ -75,7 +75,7 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/openssf-scorecard.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/pitest-analyze-pr.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/pitest-update-pr.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

.github/workflows/run-integration-tests.yml

@@ -7,22 +7,24 @@
 # https://docs.github.com/en/actions/learn-github-actions/expressions#example-returning-a-json-object
 name: "Integration tests"
 on:
-  issue_comment:
-    types: [ created ]
+#  issue_comment:
+#    types: [ created ]
+  pull_request:
 permissions:
   contents: read
 jobs:
   run-integration-tests:
     name: On-demand integration test
-    if: |
-      github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
+#    if: |
+#      github.event.issue.pull_request && contains(github.event.comment.body, '/integration-test')
     runs-on: ubuntu-24.04
     strategy:
+      fail-fast: false
       matrix:
-        integration-test: [ "checkstyle", "metrics", "prometheus-java-client" ]
+        integration-test: [ "metrics", "prometheus-java-client" ] # XXX: Dropped checkstyle.
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block
@@ -45,13 +47,14 @@ jobs:
       - name: Check out code and set up JDK and Maven
         uses: s4u/setup-maven-action@4f7fb9d9675e899ca81c6161dadbba0189a4ebb1 # v1.18.0
         with:
-          checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
+#          checkout-ref: "refs/pull/${{ github.event.issue.number }}/head"
           java-version: 17.0.13
           java-distribution: temurin
           maven-version: 3.9.9
       - name: Install project to local Maven repository
         run: mvn -T1C install -DskipTests -Dverification.skip
       - name: Run integration test
+        continue-on-error: true
         run: xvfb-run "./integration-tests/${{ matrix.integration-test }}.sh" "${{ runner.temp }}/artifacts"
       - name: Upload artifacts on failure
         if: ${{ failure() }}

.github/workflows/sonarcloud.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Install Harden-Runner
-        uses: step-security/harden-runner@c6295a65d1254861815972266d5933fd6e532bdf # v2.11.1
+        uses: step-security/harden-runner@4d991eb9b905ef189e4c376166672c3f2f230481 # v2.11.0
         with:
           disable-sudo: true
           egress-policy: block

documentation-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>documentation-support</artifactId>

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

@@ -2,7 +2,6 @@ package tech.picnic.errorprone.documentation;
 
 import static com.google.errorprone.matchers.Matchers.instanceMethod;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
-import static java.util.Objects.requireNonNull;
 import static java.util.function.Predicate.not;
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
@@ -168,10 +167,7 @@ public final class BugPatternTestExtractor implements Extractor<BugPatternTestCa
          * is safe, because this code is guarded by an earlier call to `#getClassUnderTest(..)`,
          * which ensures that `tree` is part of a longer method invocation chain.
          */
-        MethodInvocationTree inputTree =
-            (MethodInvocationTree)
-                requireNonNull(
-                    ASTHelpers.getReceiver(tree), "Instance method invocation must have receiver");
+        MethodInvocationTree inputTree = (MethodInvocationTree) ASTHelpers.getReceiver(tree);
 
         String path = ASTHelpers.constValue(inputTree.getArguments().get(0), String.class);
         Optional<String> inputCode = getSourceCode(inputTree);

error-prone-contrib/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-contrib</artifactId>
@@ -62,16 +62,6 @@
             <artifactId>auto-value-annotations</artifactId>
             <scope>provided</scope>
         </dependency>
-        <!-- XXX: JSR-305 (meta-)annotation usage by some dependencies triggers
-        NullAway to attempt to load said annotations. As such some modules
-        require these annotations to be on the classpath. Periodically review
-        whether we can drop this dependeny declaration. See
-        https://github.com/uber/NullAway/issues/1171. -->
-        <dependency>
-            <groupId>com.google.code.findbugs</groupId>
-            <artifactId>jsr305</artifactId>
-            <scope>provided</scope>
-        </dependency>
         <dependency>
             <groupId>com.google.errorprone</groupId>
             <artifactId>error_prone_annotation</artifactId>

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

@@ -11,7 +11,6 @@ import static com.google.errorprone.matchers.Matchers.not;
 import static com.google.errorprone.matchers.Matchers.returnStatement;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static com.google.errorprone.matchers.Matchers.toType;
-import static java.util.Objects.requireNonNull;
 import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
@@ -80,10 +79,7 @@ public final class DirectReturn extends BugChecker implements BlockTreeMatcher {
       return Description.NO_MATCH;
     }
 
-    Symbol variableSymbol =
-        requireNonNull(
-            ASTHelpers.getSymbol(((ReturnTree) finalStatement).getExpression()),
-            "Missing symbol for returned variable");
+    Symbol variableSymbol = ASTHelpers.getSymbol(((ReturnTree) finalStatement).getExpression());
     StatementTree precedingStatement = statements.get(statements.size() - 2);
 
     return tryMatchAssignment(variableSymbol, precedingStatement)

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

@@ -18,7 +18,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMultiset;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableTable;
-import com.google.common.collect.Iterables;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker;
@@ -34,8 +33,6 @@ import com.sun.source.tree.MethodInvocationTree;
 import com.sun.source.tree.MethodTree;
 import com.sun.tools.javac.code.Symbol.MethodSymbol;
 import com.sun.tools.javac.code.Symbol.VarSymbol;
-import com.sun.tools.javac.code.Type;
-import com.sun.tools.javac.code.Types;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
@@ -181,45 +178,30 @@ public final class ExplicitArgumentEnumeration extends BugChecker
                 state.getTypes())
             .collect(toImmutableList());
 
-    return hasLikelySuitableVarargsOverload(method, overloads, state)
+    /*
+     * If all overloads have a single parameter, and at least one of them is a varargs method, then
+     * we assume that unwrapping the iterable argument will cause a suitable overload to be invoked.
+     * (Note that there may be multiple varargs overloads, either with different parameter types, or
+     * due to method overriding; this check does not attempt to determine which exact method or
+     * overload will be invoked as a result of the suggested simplification.)
+     *
+     * Note that this is a (highly!) imperfect heuristic, but it is sufficient to prevent e.g.
+     * unwrapping of arguments to `org.jooq.impl.DSL#row`, which can cause the expression's return
+     * type to change from `RowN` to (e.g.) `Row2`.
+     */
+    // XXX: There are certainly cases where it _would_ be nice to unwrap the arguments to
+    // `org.jooq.impl.DSL#row(Collection<?>)`. Look into this.
+    // XXX: Ideally we do check that one of the overloads accepts the unwrapped arguments.
+    // XXX: Ideally we validate that eligible overloads have compatible return types.
+    boolean hasLikelySuitableVarargsOverload =
+        overloads.stream().allMatch(m -> m.params().size() == 1)
+            && overloads.stream().anyMatch(MethodSymbol::isVarArgs);
+
+    return hasLikelySuitableVarargsOverload
         ? Optional.of(SourceCode.unwrapMethodInvocation(argument, state))
         : Optional.empty();
   }
 
-  /**
-   * Tells whether it is likely that, if the argument to the given method is unwrapped, a suitable
-   * varargs overload will be invoked instead.
-   *
-   * <p>If all overloads have a single parameter, and at least one of them is a suitably-typed
-   * varargs method, then we assume that unwrapping the iterable argument will cause a suitable
-   * overload to be invoked. (Note that there may be multiple varargs overloads due to method
-   * overriding; this check does not attempt to determine which exact method or overload will be
-   * invoked as a result of the suggested simplification.)
-   *
-   * <p>Note that this is a (highly!) imperfect heuristic, but it is sufficient to prevent e.g.
-   * unwrapping of arguments to `org.jooq.impl.DSL#row`, which can cause the expression's return
-   * type to change from `RowN` to (e.g.) `Row2`.
-   */
-  // XXX: There are certainly cases where it _would_ be nice to unwrap the arguments to
-  // `org.jooq.impl.DSL#row(Collection<?>)`. Look into this.
-  // XXX: Ideally we validate that eligible overloads have compatible return types.
-  private static boolean hasLikelySuitableVarargsOverload(
-      MethodSymbol method, ImmutableList<MethodSymbol> overloads, VisitorState state) {
-    Types types = state.getTypes();
-    // XXX: This logic is fragile, as it assumes that the method parameter's type is of the form
-    // `X<T>`, where `T` is the type of the explicitly enumerated values passed to the expression to
-    // be unwrapped. This should generally hold, given the types returned by the
-    // `EXPLICIT_ITERABLE_CREATOR` expressions: `Iterable<T>`, `List<T>`, `Set<T>`, etc.
-    Type parameterType =
-        Iterables.getOnlyElement(
-            Iterables.getOnlyElement(method.getParameters()).type.getTypeArguments());
-    return overloads.stream().allMatch(m -> m.params().size() == 1)
-        && overloads.stream()
-            .filter(MethodSymbol::isVarArgs)
-            .map(m -> types.elemtype(Iterables.getOnlyElement(m.getParameters()).type))
-            .anyMatch(varArgsType -> types.containsType(parameterType, varArgsType));
-  }
-
   private static Optional<SuggestedFix> trySuggestCallingCustomAlternative(
       MethodInvocationTree tree, MethodInvocationTree argument, VisitorState state) {
     return ALTERNATIVE_METHODS.rowMap().entrySet().stream()

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

@@ -17,7 +17,6 @@ import static com.google.errorprone.matchers.Matchers.isSameType;
 import static com.google.errorprone.matchers.Matchers.methodHasParameters;
 import static com.google.errorprone.matchers.Matchers.staticMethod;
 import static com.google.errorprone.matchers.Matchers.toType;
-import static java.util.Objects.requireNonNull;
 import static java.util.function.Predicate.not;
 import static java.util.stream.Collectors.joining;
 import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
@@ -130,10 +129,7 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
       return Description.NO_MATCH;
     }
 
-    Type parameterType =
-        requireNonNull(
-            ASTHelpers.getType(Iterables.getOnlyElement(tree.getParameters())),
-            "Missing type for method parameter");
+    Type parameterType = ASTHelpers.getType(Iterables.getOnlyElement(tree.getParameters()));
 
     return findMethodSourceAnnotation(tree, state)
         .flatMap(
@@ -177,9 +173,7 @@ public final class JUnitValueSource extends BugChecker implements MethodTreeMatc
 
   private static Optional<MethodTree> findMatchingSibling(
       MethodTree tree, Predicate<? super MethodTree> predicate, VisitorState state) {
-    return requireNonNull(state.findEnclosing(ClassTree.class), "No class enclosing method")
-        .getMembers()
-        .stream()
+    return state.findEnclosing(ClassTree.class).getMembers().stream()
         .filter(MethodTree.class::isInstance)
         .map(MethodTree.class::cast)
         .filter(not(tree::equals))

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

@@ -5,7 +5,6 @@ import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.Matchers.instanceMethod;
-import static java.util.Objects.requireNonNull;
 import static tech.picnic.errorprone.utils.Documentation.BUG_PATTERNS_BASE_URL;
 
 import com.google.auto.service.AutoService;
@@ -87,9 +86,7 @@ public final class NonEmptyMono extends BugChecker implements MethodInvocationTr
       return Description.NO_MATCH;
     }
 
-    ExpressionTree receiver =
-        requireNonNull(
-            ASTHelpers.getReceiver(tree), "Instance method invocation must have receiver");
+    ExpressionTree receiver = ASTHelpers.getReceiver(tree);
     if (!NON_EMPTY_MONO.matches(receiver, state)) {
       return Description.NO_MATCH;
     }

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

@@ -204,11 +204,6 @@ final class AssertJEnumerableRules {
       return enumAssert.hasSize(iterable.length);
     }
 
-    @BeforeTemplate
-    EnumerableAssert<?, S> before(EnumerableAssert<?, S> enumAssert, CharSequence iterable) {
-      return enumAssert.hasSize(iterable.length());
-    }
-
     @AfterTemplate
     EnumerableAssert<?, S> after(EnumerableAssert<?, S> enumAssert, Iterable<E> iterable) {
       return enumAssert.hasSameSizeAs(iterable);

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

@@ -515,14 +515,8 @@ final class ReactorRules {
           mono.switchIfEmpty(Mono.empty()), mono.flux().next(), mono.flux().singleOrEmpty());
     }
 
-    // XXX: Consider filing a SonarCloud issue for the S2637 false positive.
     @BeforeTemplate
-    @SuppressWarnings({
-      "java:S2637" /* False positive: result is never `null`. */,
-      "java:S4968" /* Result may be `Mono<Void>`. */,
-      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
-    })
-    Mono<? extends @Nullable Void> before2(Mono<@Nullable Void> mono) {
+    Mono<@Nullable Void> before2(Mono<@Nullable Void> mono) {
       return Refaster.anyOf(mono.ignoreElement(), mono.then());
     }
 
@@ -951,8 +945,7 @@ final class ReactorRules {
   /** Prefer direct invocation of {@link Mono#then()}} over more contrived alternatives. */
   static final class MonoThen<T> {
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before(Mono<T> mono) {
+    Mono<@Nullable Void> before(Mono<T> mono) {
       return Refaster.anyOf(
           mono.ignoreElement().then(),
           mono.flux().then(),
@@ -961,8 +954,7 @@ final class ReactorRules {
     }
 
     @AfterTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> after(Mono<T> mono) {
+    Mono<@Nullable Void> after(Mono<T> mono) {
       return mono.then();
     }
   }
@@ -970,25 +962,17 @@ final class ReactorRules {
   /** Avoid vacuous invocations of {@link Flux#ignoreElements()}. */
   static final class FluxThen<T> {
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before(Flux<T> flux) {
+    Mono<@Nullable Void> before(Flux<T> flux) {
       return flux.ignoreElements().then();
     }
 
-    // XXX: Consider filing a SonarCloud issue for the S2637 false positive.
     @BeforeTemplate
-    @SuppressWarnings({
-      "java:S2637" /* False positive: result is never `null`. */,
-      "java:S4968" /* Result may be `Mono<Void>`. */,
-      "key-to-resolve-AnnotationUseStyle-and-TrailingComment-check-conflict"
-    })
-    Mono<? extends @Nullable Void> before2(Flux<@Nullable Void> flux) {
+    Mono<@Nullable Void> before2(Flux<@Nullable Void> flux) {
       return flux.ignoreElements();
     }
 
     @AfterTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> after(Flux<T> flux) {
+    Mono<@Nullable Void> after(Flux<T> flux) {
       return flux.then();
     }
   }
@@ -996,14 +980,12 @@ final class ReactorRules {
   /** Avoid vacuous invocations of {@link Mono#ignoreElement()}. */
   static final class MonoThenEmpty<T> {
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before(Mono<T> mono, Publisher<@Nullable Void> publisher) {
+    Mono<@Nullable Void> before(Mono<T> mono, Publisher<@Nullable Void> publisher) {
       return mono.ignoreElement().thenEmpty(publisher);
     }
 
     @AfterTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> after(Mono<T> mono, Publisher<@Nullable Void> publisher) {
+    Mono<@Nullable Void> after(Mono<T> mono, Publisher<@Nullable Void> publisher) {
       return mono.thenEmpty(publisher);
     }
   }
@@ -1011,14 +993,12 @@ final class ReactorRules {
   /** Avoid vacuous invocations of {@link Flux#ignoreElements()}. */
   static final class FluxThenEmpty<T> {
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before(Flux<T> flux, Publisher<@Nullable Void> publisher) {
+    Mono<@Nullable Void> before(Flux<T> flux, Publisher<@Nullable Void> publisher) {
       return flux.ignoreElements().thenEmpty(publisher);
     }
 
     @AfterTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> after(Flux<T> flux, Publisher<@Nullable Void> publisher) {
+    Mono<@Nullable Void> after(Flux<T> flux, Publisher<@Nullable Void> publisher) {
       return flux.thenEmpty(publisher);
     }
   }
@@ -1074,8 +1054,7 @@ final class ReactorRules {
     }
 
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before2(Mono<T> mono1, Mono<@Nullable Void> mono2) {
+    Mono<@Nullable Void> before2(Mono<T> mono1, Mono<@Nullable Void> mono2) {
       return mono1.thenEmpty(mono2);
     }
 
@@ -1093,8 +1072,7 @@ final class ReactorRules {
     }
 
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before2(Flux<T> flux, Mono<@Nullable Void> mono) {
+    Mono<@Nullable Void> before2(Flux<T> flux, Mono<@Nullable Void> mono) {
       return flux.thenEmpty(mono);
     }
 

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

@@ -23,16 +23,14 @@ final class RxJava2AdapterRules {
   /** Use the fluent API style when using {@link RxJava2Adapter#completableToMono}. */
   static final class CompletableToMono {
     @BeforeTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> before(Completable completable) {
+    Mono<@Nullable Void> before(Completable completable) {
       return Refaster.anyOf(
           RxJava2Adapter.completableToMono(completable),
           completable.to(RxJava2Adapter::completableToMono));
     }
 
     @AfterTemplate
-    @SuppressWarnings("java:S4968" /* Result may be `Mono<Void>`. */)
-    Mono<? extends @Nullable Void> after(Completable completable) {
+    Mono<@Nullable Void> after(Completable completable) {
       return completable.as(RxJava2Adapter::completableToMono);
     }
   }

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

@@ -16,8 +16,6 @@ final class ExplicitArgumentEnumerationTest {
             "import com.google.common.collect.ImmutableList;",
             "import com.google.errorprone.CompilationTestHelper;",
             "import com.google.errorprone.bugpatterns.BugChecker;",
-            "import io.micrometer.core.instrument.Counter;",
-            "import io.micrometer.core.instrument.Tag;",
             "import org.jooq.impl.DSL;",
             "import reactor.core.publisher.Flux;",
             "import reactor.test.StepVerifier;",
@@ -34,8 +32,6 @@ final class ExplicitArgumentEnumerationTest {
             "",
             "    DSL.row(ImmutableList.of(1, 2));",
             "",
-            "    Counter.builder(\"foo\").tags(ImmutableList.of(Tag.of(\"bar\", \"baz\")));",
-            "",
             "    // BUG: Diagnostic contains:",
             "    unaryMethod(ImmutableList.of(1, 2));",
             "    unaryMethodWithLessVisibleOverload(ImmutableList.of(1, 2));",

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

@@ -67,11 +67,10 @@ final class AssertJEnumerableRulesTest implements RefasterRuleCollectionTestCase
         assertThat(ImmutableSet.of(4)).size().isBetween(5, 6));
   }
 
-  ImmutableSet<EnumerableAssert<?, Character>> testEnumerableAssertHasSameSizeAs() {
+  ImmutableSet<EnumerableAssert<?, Integer>> testEnumerableAssertHasSameSizeAs() {
     return ImmutableSet.of(
-        assertThat("foo").hasSize(Iterables.size(ImmutableSet.of(1))),
-        assertThat("bar").hasSize(ImmutableSet.of(2).size()),
-        assertThat("baz").hasSize(new Integer[0].length),
-        assertThat("qux").hasSize("quux".length()));
+        assertThat(ImmutableSet.of(1)).hasSize(Iterables.size(ImmutableSet.of(2))),
+        assertThat(ImmutableSet.of(3)).hasSize(ImmutableSet.of(4).size()),
+        assertThat(ImmutableSet.of(5)).hasSize(new Integer[0].length));
   }
 }

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

@@ -66,11 +66,10 @@ final class AssertJEnumerableRulesTest implements RefasterRuleCollectionTestCase
         assertThat(ImmutableSet.of(4)).hasSizeBetween(5, 6));
   }
 
-  ImmutableSet<EnumerableAssert<?, Character>> testEnumerableAssertHasSameSizeAs() {
+  ImmutableSet<EnumerableAssert<?, Integer>> testEnumerableAssertHasSameSizeAs() {
     return ImmutableSet.of(
-        assertThat("foo").hasSameSizeAs(ImmutableSet.of(1)),
-        assertThat("bar").hasSameSizeAs(ImmutableSet.of(2)),
-        assertThat("baz").hasSameSizeAs(new Integer[0]),
-        assertThat("qux").hasSameSizeAs("quux"));
+        assertThat(ImmutableSet.of(1)).hasSameSizeAs(ImmutableSet.of(2)),
+        assertThat(ImmutableSet.of(3)).hasSameSizeAs(ImmutableSet.of(4)),
+        assertThat(ImmutableSet.of(5)).hasSameSizeAs(new Integer[0]));
   }
 }

error-prone-experimental/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-experimental</artifactId>

error-prone-experimental/src/main/java/tech/picnic/errorprone/experimental/bugpatterns/MethodReferenceUsage.java

@@ -29,7 +29,6 @@ import com.sun.source.tree.ReturnTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
 import com.sun.tools.javac.code.Symbol;
-import com.sun.tools.javac.code.Symbol.PackageSymbol;
 import com.sun.tools.javac.code.Type;
 import java.util.List;
 import java.util.Optional;
@@ -127,7 +126,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
         return Optional.empty();
       }
 
-      Symbol sym = ASTHelpers.getSymbol(subTree);
+      Symbol sym = ASTHelpers.getSymbol(methodSelect);
       return ASTHelpers.isStatic(sym)
           ? constructFix(lambdaExpr, sym.owner, methodSelect)
           : constructFix(lambdaExpr, "this", methodSelect);
@@ -201,8 +200,7 @@ public final class MethodReferenceUsage extends BugChecker implements LambdaExpr
     Name sName = target.getSimpleName();
     Optional<SuggestedFix.Builder> fix = constructFix(lambdaExpr, sName, methodName);
 
-    PackageSymbol pkg = ASTHelpers.enclosingPackage(target);
-    if (pkg != null && !"java.lang".equals(pkg.toString())) {
+    if (!"java.lang".equals(ASTHelpers.enclosingPackage(target).toString())) {
       Name fqName = target.getQualifiedName();
       if (!sName.equals(fqName)) {
         return fix.map(b -> b.addImport(fqName.toString()));

error-prone-guidelines/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-guidelines</artifactId>

error-prone-utils/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>error-prone-utils</artifactId>

error-prone-utils/src/main/java/tech/picnic/errorprone/utils/AnnotationAttributeMatcher.java

@@ -1,7 +1,5 @@
 package tech.picnic.errorprone.utils;
 
-import static java.util.Objects.requireNonNull;
-
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableSet;
@@ -117,15 +115,9 @@ public final class AnnotationAttributeMatcher implements Serializable {
   }
 
   private static String extractAttributeName(ExpressionTree expr) {
-    if (!(expr instanceof AssignmentTree assignment)) {
-      return "value";
-    }
-
-    return requireNonNull(
-            ASTHelpers.getSymbol(assignment.getVariable()),
-            "Missing symbol for annotation attribute")
-        .getSimpleName()
-        .toString();
+    return (expr instanceof AssignmentTree assignment)
+        ? ASTHelpers.getSymbol(assignment.getVariable()).getSimpleName().toString()
+        : "value";
   }
 
   // XXX: The caller of this method can be implemented more efficiently in case of a "wholeTypes"

integration-tests/metrics-init.patch

@@ -38,7 +38,7 @@
 +            <dependency>
 +                <groupId>com.google.guava</groupId>
 +                <artifactId>guava</artifactId>
-+                <version>33.4.7-jre<!-- Renovate: com.google.guava:guava-bom --></version>
++                <version>33.4.0-jre<!-- Renovate: com.google.guava:guava-bom --></version>
 +            </dependency>
 +        </dependencies>
 +    </dependencyManagement>

pom.xml

@@ -4,7 +4,7 @@
 
     <groupId>tech.picnic.error-prone-support</groupId>
     <artifactId>error-prone-support</artifactId>
-    <version>0.22.0</version>
+    <version>0.21.1-SNAPSHOT</version>
     <packaging>pom</packaging>
 
     <name>Picnic :: Error Prone Support</name>
@@ -52,7 +52,7 @@
 
     <scm child.scm.developerConnection.inherit.append.path="false" child.scm.url.inherit.append.path="false">
         <developerConnection>scm:git:git@github.com:PicnicSupermarket/error-prone-support.git</developerConnection>
-        <tag>v0.22.0</tag>
+        <tag>HEAD</tag>
         <url>https://github.com/PicnicSupermarket/error-prone-support</url>
     </scm>
     <issueManagement>
@@ -146,7 +146,7 @@
         <error-prone.self-check-args />
         <!-- The build timestamp is derived from the most recent commit
         timestamp in support of reproducible builds. -->
-        <project.build.outputTimestamp>2025-04-14T09:34:39Z</project.build.outputTimestamp>
+        <project.build.outputTimestamp>2025-03-24T10:41:07Z</project.build.outputTimestamp>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <!-- Glob pattern identifying Refaster rule definition files. These
         Java classes don't contain "regular" code, and thus require special
@@ -210,12 +210,16 @@
         <version.error-prone-slf4j>0.1.28</version.error-prone-slf4j>
         <version.guava-beta-checker>1.0</version.guava-beta-checker>
         <version.jdk>17</version.jdk>
+        <version.jmh>1.37</version.jmh>
         <version.maven>3.9.9</version.maven>
         <version.mockito>5.17.0</version.mockito>
-        <version.nopen-checker>1.0.1</version.nopen-checker>
-        <version.nullaway>0.12.6</version.nullaway>
-        <version.pitest-git>2.2.1</version.pitest-git>
-        <version.rewrite-templating>1.25.1</version.rewrite-templating>
+        <!-- XXX: Consider providing our own implementation with similar
+        functionality, and designing it such that JMH classes would not need to
+        be annotated `@Open`. -->
+        <version.nopen>1.0.1</version.nopen>
+        <version.nullaway>0.12.5</version.nullaway>
+        <version.pitest-git>2.2.0</version.pitest-git>
+        <version.rewrite-templating>1.24.2</version.rewrite-templating>
         <version.surefire>3.2.3</version.surefire>
     </properties>
 
@@ -303,16 +307,6 @@
                 <artifactId>auto-value-annotations</artifactId>
                 <version>${version.auto-value}</version>
             </dependency>
-            <!-- XXX: JSR-305 (meta-)annotation usage by some dependencies
-            triggers NullAway to attempt to load said annotations. As such
-            some modules require these annotations to be on the classpath.
-            Periodically review whether we can drop this dependeny version
-            declaration. See https://github.com/uber/NullAway/issues/1171. -->
-            <dependency>
-                <groupId>com.google.code.findbugs</groupId>
-                <artifactId>jsr305</artifactId>
-                <version>3.0.2</version>
-            </dependency>
             <dependency>
                 <groupId>com.google.errorprone</groupId>
                 <artifactId>error_prone_annotation</artifactId>
@@ -351,7 +345,7 @@
             <dependency>
                 <groupId>com.google.guava</groupId>
                 <artifactId>guava-bom</artifactId>
-                <version>33.4.7-jre</version>
+                <version>33.4.0-jre</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -360,10 +354,15 @@
                 <artifactId>truth</artifactId>
                 <version>1.4.4</version>
             </dependency>
+            <dependency>
+                <groupId>com.jakewharton.nopen</groupId>
+                <artifactId>nopen-annotations</artifactId>
+                <version>${version.nopen}</version>
+            </dependency>
             <dependency>
                 <groupId>com.jakewharton.nopen</groupId>
                 <artifactId>nopen-checker</artifactId>
-                <version>${version.nopen-checker}</version>
+                <version>${version.nopen}</version>
             </dependency>
             <dependency>
                 <groupId>com.uber.nullaway</groupId>
@@ -397,7 +396,7 @@
             <dependency>
                 <groupId>io.swagger.core.v3</groupId>
                 <artifactId>swagger-annotations</artifactId>
-                <version>2.2.30</version>
+                <version>2.2.29</version>
             </dependency>
             <dependency>
                 <groupId>jakarta.servlet</groupId>
@@ -445,7 +444,7 @@
             <dependency>
                 <groupId>org.aspectj</groupId>
                 <artifactId>aspectjweaver</artifactId>
-                <version>1.9.24</version>
+                <version>1.9.23</version>
             </dependency>
             <dependency>
                 <groupId>org.assertj</groupId>
@@ -457,7 +456,7 @@
             <dependency>
                 <groupId>org.checkerframework</groupId>
                 <artifactId>checker-qual</artifactId>
-                <version>3.49.2</version>
+                <version>3.49.1</version>
             </dependency>
             <dependency>
                 <groupId>org.hamcrest</groupId>
@@ -482,7 +481,7 @@
             <dependency>
                 <groupId>org.junit</groupId>
                 <artifactId>junit-bom</artifactId>
-                <version>5.12.2</version>
+                <version>5.12.1</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -500,6 +499,16 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <dependency>
+                <groupId>org.openjdk.jmh</groupId>
+                <artifactId>jmh-core</artifactId>
+                <version>${version.jmh}</version>
+            </dependency>
+            <dependency>
+                <groupId>org.openjdk.jmh</groupId>
+                <artifactId>jmh-generator-annprocess</artifactId>
+                <version>${version.jmh}</version>
+            </dependency>
             <dependency>
                 <groupId>org.openrewrite</groupId>
                 <artifactId>rewrite-templating</artifactId>
@@ -508,7 +517,7 @@
             <dependency>
                 <groupId>org.openrewrite.recipe</groupId>
                 <artifactId>rewrite-recipe-bom</artifactId>
-                <version>3.6.1</version>
+                <version>3.5.0</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
@@ -624,7 +633,6 @@
                     <configuration>
                         <bundledSignatures>
                             <bundledSignature>jdk-internal</bundledSignature>
-                            <bundledSignature>jdk-reflection</bundledSignature>
                             <bundledSignature>jdk-system-out</bundledSignature>
                             <!-- Other bundles are available but currently not
                             enabled:
@@ -634,6 +642,10 @@
                             - jdk-deprecated: we compile with `-Xlint:all`,
                               which causes the build to fail when _any_
                               deprecated method is called.
+                            - jdk-reflection: this bundle should probably be
+                              enabled, but currently
+                              `java.lang.reflect.AccessibleObject#setAccessible`
+                              is still called in various places.
                             - jdk-non-portable: the Error Prone integration
                               crucially relies on some of these APIs.
                             - jdk-unsafe: see
@@ -935,7 +947,7 @@
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>10.23.0</version>
+                            <version>10.22.0</version>
                         </dependency>
                         <dependency>
                             <groupId>io.spring.nohttp</groupId>
@@ -971,6 +983,11 @@
                                 <artifactId>auto-value</artifactId>
                                 <version>${version.auto-value}</version>
                             </path>
+                            <path>
+                                <groupId>com.google.auto.value</groupId>
+                                <artifactId>auto-value</artifactId>
+                                <version>${version.auto-value}</version>
+                            </path>
                             <path>
                                 <groupId>com.google.auto.service</groupId>
                                 <artifactId>auto-service</artifactId>
@@ -981,6 +998,10 @@
                                 <artifactId>rewrite-templating</artifactId>
                                 <version>${version.rewrite-templating}</version>
                             </path>
+                            <path>
+                                <groupId>org.openjdk.jmh</groupId>
+                                <artifactId>jmh-generator-annprocess</artifactId>
+                            </path>
                         </annotationProcessorPaths>
                         <compilerArgs>
                             <arg>--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
@@ -1324,6 +1345,11 @@
                         <redirectTestOutputToFile>true</redirectTestOutputToFile>
                     </configuration>
                 </plugin>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>exec-maven-plugin</artifactId>
+                    <version>3.1.1</version>
+                </plugin>
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>license-maven-plugin</artifactId>
@@ -1421,6 +1447,7 @@
                                 GPL-2.0-with-classpath-exception
                                 | CDDL/GPLv2+CE
                                 | CDDL + GPLv2 with classpath exception
+                                | GNU General Public License (GPL), version 2, with the Classpath exception
                                 | GNU General Public License, version 2 (GPL2), with the classpath exception
                                 | GNU General Public License, version 2, with the Classpath Exception
                                 | GPL2 w/ CPE
@@ -1537,7 +1564,7 @@
                 <plugin>
                     <groupId>org.pitest</groupId>
                     <artifactId>pitest-maven</artifactId>
-                    <version>1.19.1</version>
+                    <version>1.19.0</version>
                     <configuration>
                         <excludedClasses>
                             <!-- AutoValue generated classes. -->
@@ -1878,7 +1905,7 @@
                                 <path>
                                     <groupId>com.jakewharton.nopen</groupId>
                                     <artifactId>nopen-checker</artifactId>
-                                    <version>${version.nopen-checker}</version>
+                                    <version>${version.nopen}</version>
                                 </path>
                                 <path>
                                     <groupId>com.uber.nullaway</groupId>
@@ -1950,7 +1977,6 @@
                                     -XepOpt:NullAway:AnnotatedPackages=tech.picnic
                                     -XepOpt:NullAway:AssertsEnabled=true
                                     -XepOpt:NullAway:CheckOptionalEmptiness=true
-                                    -XepOpt:NullAway:JSpecifyMode=true
                                     -XepOpt:Nullness:Conservative=false
                                     -XepOpt:StatementSwitchToExpressionSwitch:EnableDirectConversion=true
                                     <!-- Append additional custom arguments. -->
@@ -2166,5 +2192,66 @@
                 </plugins>
             </build>
         </profile>
+        <profile>
+            <!-- Enables execution of a JMH benchmark. Given a benchmark class
+            `tech.picnic.MyBenchmark`, the following command (executed against
+            the (sub)module in which the benchmark resides) will compile and
+            execute said benchmark:
+
+              mvn process-test-classes -Dverification.skip \
+                -Djmh.run-benchmark=tech.picnic.MyBenchmark
+            -->
+            <id>run-jmh-benchmark</id>
+            <activation>
+                <property>
+                    <name>jmh.run-benchmark</name>
+                </property>
+            </activation>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-dependency-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <id>build-jmh-runtime-classpath</id>
+                                <goals>
+                                    <goal>build-classpath</goal>
+                                </goals>
+                                <configuration>
+                                    <outputProperty>testClasspath</outputProperty>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>exec-maven-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <id>run-jmh-benchmark</id>
+                                <goals>
+                                    <goal>java</goal>
+                                </goals>
+                                <phase>process-test-classes</phase>
+                                <configuration>
+                                    <classpathScope>test</classpathScope>
+                                    <mainClass>${jmh.run-benchmark}</mainClass>
+                                    <systemProperties>
+                                        <!-- The runtime classpath is defined
+                                        in this way so that any JVMs forked by
+                                        JMH will have the desired classpath. -->
+                                        <systemProperty>
+                                            <key>java.class.path</key>
+                                            <value>${project.build.testOutputDirectory}${path.separator}${project.build.outputDirectory}${path.separator}${testClasspath}</value>
+                                        </systemProperty>
+                                    </systemProperties>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
     </profiles>
 </project>

refaster-compiler/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-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>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-runner</artifactId>
@@ -26,13 +26,21 @@
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>refaster-support</artifactId>
-            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.auto</groupId>
+            <artifactId>auto-common</artifactId>
+            <scope>provided</scope>
         </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>
+        </dependency>
         <dependency>
             <groupId>com.google.errorprone</groupId>
             <artifactId>error_prone_annotation</artifactId>
@@ -48,6 +56,11 @@
             <artifactId>error_prone_check_api</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.errorprone</groupId>
+            <artifactId>error_prone_core</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>com.google.errorprone</groupId>
             <artifactId>error_prone_test_helpers</artifactId>
@@ -58,6 +71,11 @@
             <artifactId>guava</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>com.jakewharton.nopen</groupId>
+            <artifactId>nopen-annotations</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>javax.annotation</groupId>
             <artifactId>javax.annotation-api</artifactId>
@@ -95,6 +113,11 @@
             <artifactId>junit-jupiter-params</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.openrewrite</groupId>
             <artifactId>rewrite-core</artifactId>

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

@@ -0,0 +1,126 @@
+package tech.picnic.errorprone.refaster.runner;
+
+import static java.util.Comparator.comparingInt;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSortedSet;
+import com.google.common.collect.Maps;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+/**
+ * A node in an immutable tree.
+ *
+ * <p>The tree's edges are string-labeled, while its leaves store values of type {@code T}.
+ */
+@AutoValue
+abstract class Node<T> {
+  // XXX: Review: should this method accept a `SetMultimap<V, ? extends Set<String>>`, or should
+  // there be such an overload?
+  static <T> Node<T> create(
+      Set<T> values, Function<? super T, ? extends Set<? extends Set<String>>> pathExtractor) {
+    Builder<T> tree = Builder.create();
+    tree.register(values, pathExtractor);
+    return tree.build();
+  }
+
+  abstract ImmutableMap<String, Node<T>> children();
+
+  abstract ImmutableList<T> values();
+
+  // XXX: Consider having `RefasterRuleSelector` already collect the candidate edges into a
+  // `SortedSet`, as that would likely speed up `ImmutableSortedSet#copyOf`.
+  // XXX: If this ^ proves worthwhile, then the test code and benchmark should be updated
+  // accordingly.
+  void collectReachableValues(Set<String> candidateEdges, Consumer<T> sink) {
+    collectReachableValues(ImmutableSortedSet.copyOf(candidateEdges).asList(), sink);
+  }
+
+  private void collectReachableValues(ImmutableList<String> candidateEdges, Consumer<T> sink) {
+    values().forEach(sink);
+
+    if (candidateEdges.isEmpty() || children().isEmpty()) {
+      return;
+    }
+
+    /*
+     * For performance reasons we iterate over the smallest set of edges. In case there are fewer
+     * children than candidate edges we iterate over the former, at the cost of not pruning the set
+     * of candidate edges if a transition is made.
+     */
+    int candidateEdgeCount = candidateEdges.size();
+    if (children().size() < candidateEdgeCount) {
+      for (Map.Entry<String, Node<T>> e : children().entrySet()) {
+        if (candidateEdges.contains(e.getKey())) {
+          e.getValue().collectReachableValues(candidateEdges, sink);
+        }
+      }
+    } else {
+      for (int i = 0; i < candidateEdgeCount; i++) {
+        Node<T> child = children().get(candidateEdges.get(i));
+        if (child != null) {
+          child.collectReachableValues(candidateEdges.subList(i + 1, candidateEdgeCount), sink);
+        }
+      }
+    }
+  }
+
+  @AutoValue
+  @SuppressWarnings("AutoValueImmutableFields" /* Type is used only during `Node` construction. */)
+  abstract static class Builder<T> {
+    private static <T> Builder<T> create() {
+      return new AutoValue_Node_Builder<>(new HashMap<>(), new ArrayList<>());
+    }
+
+    abstract Map<String, Builder<T>> children();
+
+    abstract List<T> values();
+
+    /**
+     * Registers all paths to each of the given values.
+     *
+     * <p>Shorter paths are registered first, so that longer paths can be skipped if a strict prefix
+     * leads to the same value.
+     */
+    private void register(
+        Set<T> values, Function<? super T, ? extends Set<? extends Set<String>>> pathsExtractor) {
+      for (T value : values) {
+        List<? extends Set<String>> paths = new ArrayList<>(pathsExtractor.apply(value));
+        /*
+         * We sort paths by length ascending, so that in case of two paths where one is an initial
+         * prefix of the other, only the former is encoded (thus saving some space).
+         */
+        paths.sort(comparingInt(Set::size));
+        paths.forEach(path -> registerPath(value, ImmutableList.sortedCopyOf(path)));
+      }
+    }
+
+    private void registerPath(T value, ImmutableList<String> path) {
+      if (values().contains(value)) {
+        /* Another (shorter) path already leads to this value. */
+        return;
+      }
+
+      if (path.isEmpty()) {
+        values().add(value);
+      } else {
+        children()
+            .computeIfAbsent(path.get(0), k -> create())
+            .registerPath(value, path.subList(1, path.size()));
+      }
+    }
+
+    private Node<T> build() {
+      return new AutoValue_Node<>(
+          ImmutableMap.copyOf(Maps.transformValues(children(), Builder::build)),
+          ImmutableList.copyOf(values()));
+    }
+  }
+}

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

@@ -21,7 +21,6 @@ import com.google.common.collect.TreeRangeSet;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.BugPattern.SeverityLevel;
 import com.google.errorprone.CodeTransformer;
-import com.google.errorprone.CompositeCodeTransformer;
 import com.google.errorprone.ErrorProneFlags;
 import com.google.errorprone.ErrorProneOptions.Severity;
 import com.google.errorprone.SubContext;
@@ -39,6 +38,7 @@ import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 import javax.inject.Inject;
@@ -64,8 +64,9 @@ public final class Refaster extends BugChecker implements CompilationUnitTreeMat
 
   private static final long serialVersionUID = 1L;
 
+  // XXX: Review this suppression.
   @SuppressWarnings({"java:S1948", "serial"} /* Concrete instance will be `Serializable`. */)
-  private final CodeTransformer codeTransformer;
+  private final RefasterRuleSelector ruleSelector;
 
   /** Instantiates a default {@link Refaster} instance. */
   public Refaster() {
@@ -80,16 +81,29 @@ public final class Refaster extends BugChecker implements CompilationUnitTreeMat
   @Inject
   @VisibleForTesting
   public Refaster(ErrorProneFlags flags) {
-    codeTransformer = createCompositeCodeTransformer(flags);
+    ruleSelector = createRefasterRuleSelector(flags);
   }
 
   @CanIgnoreReturnValue
   @Override
   public Description matchCompilationUnit(CompilationUnitTree tree, VisitorState state) {
-    /* First, collect all matches. */
-    List<Description> matches = new ArrayList<>();
-    codeTransformer.apply(state.getPath(), new SubContext(state.context), matches::add);
+    Set<CodeTransformer> candidateTransformers = ruleSelector.selectCandidateRules(tree);
 
+    /* First, collect all matches. */
+    SubContext context = new SubContext(state.context);
+    List<Description> matches = new ArrayList<>();
+    for (CodeTransformer transformer : candidateTransformers) {
+      try {
+        transformer.apply(state.getPath(), context, matches::add);
+      } catch (LinkageError e) {
+        // XXX: This `try/catch` block handles the issue described and resolved in
+        // https://github.com/google/error-prone/pull/2456. Drop this block once that change is
+        // released.
+        // XXX: Find a way to identify that we're running Picnic's Error Prone fork and disable this
+        // fallback if so, as it might hide other bugs.
+        return Description.NO_MATCH;
+      }
+    }
     /* Then apply them. */
     applyMatches(matches, ((JCCompilationUnit) tree).endPositions, state);
 
@@ -193,10 +207,12 @@ public final class Refaster extends BugChecker implements CompilationUnitTreeMat
     return description.fixes.stream().flatMap(fix -> fix.getReplacements(endPositions).stream());
   }
 
-  private static CodeTransformer createCompositeCodeTransformer(ErrorProneFlags flags) {
+  // XXX: Add a flag to disable the optimized `RefasterRuleSelector`. That would allow us to verify
+  // that we're not prematurely pruning rules.
+  private static RefasterRuleSelector createRefasterRuleSelector(ErrorProneFlags flags) {
     ImmutableListMultimap<String, CodeTransformer> allTransformers =
         CodeTransformers.getAllCodeTransformers();
-    return CompositeCodeTransformer.compose(
+    return RefasterRuleSelector.create(
         flags
             .get(INCLUDED_RULES_PATTERN_FLAG)
             .map(Pattern::compile)

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

@@ -0,0 +1,510 @@
+package tech.picnic.errorprone.refaster.runner;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static java.util.Collections.newSetFromMap;
+import static java.util.stream.Collectors.toCollection;
+
+import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.errorprone.CodeTransformer;
+import com.google.errorprone.CompositeCodeTransformer;
+import com.google.errorprone.refaster.BlockTemplate;
+import com.google.errorprone.refaster.ExpressionTemplate;
+import com.google.errorprone.refaster.RefasterRule;
+import com.google.errorprone.refaster.UAnyOf;
+import com.google.errorprone.refaster.UExpression;
+import com.google.errorprone.refaster.UStatement;
+import com.google.errorprone.refaster.UStaticIdent;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import com.sun.source.tree.AssignmentTree;
+import com.sun.source.tree.BinaryTree;
+import com.sun.source.tree.ClassTree;
+import com.sun.source.tree.CompilationUnitTree;
+import com.sun.source.tree.CompoundAssignmentTree;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.IdentifierTree;
+import com.sun.source.tree.MemberReferenceTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.source.tree.PackageTree;
+import com.sun.source.tree.Tree;
+import com.sun.source.tree.UnaryTree;
+import com.sun.source.tree.VariableTree;
+import com.sun.source.util.TreeScanner;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import org.jspecify.annotations.Nullable;
+import tech.picnic.errorprone.refaster.AnnotatedCompositeCodeTransformer;
+
+// XXX: Add some examples of which source files would match what templates in the tree.
+// XXX: Consider this text in general.
+/**
+ * A {@link RefasterRuleSelector} algorithm that selects Refaster templates based on the content of
+ * a {@link CompilationUnitTree}.
+ *
+ * <p>The algorithm consists of the following steps:
+ *
+ * <ol>
+ *   <li>Create a {@link Node tree} structure based on the provided Refaster templates.
+ *       <ol>
+ *         <li>Extract all identifiers from the {@link BeforeTemplate}s.
+ *         <li>Sort identifiers lexicographically and collect into a set.
+ *         <li>Add a path to the tree based on the sorted identifiers.
+ *       </ol>
+ *   <li>Extract all identifiers from the {@link CompilationUnitTree} and sort them
+ *       lexicographically.
+ *   <li>Traverse the tree based on the identifiers from the {@link CompilationUnitTree}. Every node
+ *       can contain Refaster templates. Once a node is we found a candidate Refaster template that
+ *       might match some code and will therefore be added to the list of candidates.
+ * </ol>
+ *
+ * <p>This is an example to explain the algorithm. Consider the templates with identifiers; {@code
+ * T1 = [A, B, C]}, {@code T2 = [B]}, and {@code T3 = [B, D]}. This will result in the following
+ * tree structure:
+ *
+ * <pre>{@code
+ * <root>
+ *    ├── A
+ *    │   └── B
+ *    │       └── C -- T1
+ *    └── B         -- T2
+ *        └── D     -- T3
+ * }</pre>
+ *
+ * <p>The tree is traversed based on the identifiers in the {@link CompilationUnitTree}. When a node
+ * containing a template is reached, we can be certain that the identifiers from the {@link
+ * BeforeTemplate} are at least present in the {@link CompilationUnitTree}.
+ *
+ * <p>Since the identifiers are sorted, we can skip parts of the {@link Node tree} while we are
+ * traversing it. Instead of trying to match all Refaster templates against every expression in a
+ * {@link CompilationUnitTree} we now only matching a subset of the templates that at least have a
+ * chance of matching. As a result, the performance of Refaster increases significantly.
+ */
+final class RefasterRuleSelector {
+  private final Node<CodeTransformer> codeTransformers;
+
+  private RefasterRuleSelector(Node<CodeTransformer> codeTransformers) {
+    this.codeTransformers = codeTransformers;
+  }
+
+  /**
+   * Instantiates a new {@link RefasterRuleSelector} backed by the given {@link CodeTransformer}s.
+   */
+  static RefasterRuleSelector create(ImmutableCollection<CodeTransformer> refasterRules) {
+    Map<CodeTransformer, ImmutableSet<ImmutableSet<String>>> ruleIdentifiersByTransformer =
+        indexRuleIdentifiers(refasterRules);
+    return new RefasterRuleSelector(
+        Node.create(ruleIdentifiersByTransformer.keySet(), ruleIdentifiersByTransformer::get));
+  }
+
+  /**
+   * Retrieves a set of Refaster templates that can possibly match based on a {@link
+   * CompilationUnitTree}.
+   *
+   * @param tree The {@link CompilationUnitTree} for which candidate Refaster templates are
+   *     selected.
+   * @return Set of Refaster templates that can possibly match in the provided {@link
+   *     CompilationUnitTree}.
+   */
+  Set<CodeTransformer> selectCandidateRules(CompilationUnitTree tree) {
+    Set<CodeTransformer> candidateRules = newSetFromMap(new IdentityHashMap<>());
+    codeTransformers.collectReachableValues(extractSourceIdentifiers(tree), candidateRules::add);
+    return candidateRules;
+  }
+
+  private static Map<CodeTransformer, ImmutableSet<ImmutableSet<String>>> indexRuleIdentifiers(
+      ImmutableCollection<CodeTransformer> codeTransformers) {
+    IdentityHashMap<CodeTransformer, ImmutableSet<ImmutableSet<String>>> identifiers =
+        new IdentityHashMap<>();
+    for (CodeTransformer transformer : codeTransformers) {
+      collectRuleIdentifiers(transformer, identifiers);
+    }
+    return identifiers;
+  }
+
+  private static void collectRuleIdentifiers(
+      CodeTransformer codeTransformer,
+      Map<CodeTransformer, ImmutableSet<ImmutableSet<String>>> identifiers) {
+    if (codeTransformer instanceof CompositeCodeTransformer compositeCodeTransformer) {
+      for (CodeTransformer transformer : compositeCodeTransformer.transformers()) {
+        collectRuleIdentifiers(transformer, identifiers);
+      }
+    } else if (codeTransformer instanceof AnnotatedCompositeCodeTransformer annotatedTransformer) {
+      for (Map.Entry<CodeTransformer, ImmutableSet<ImmutableSet<String>>> e :
+          indexRuleIdentifiers(annotatedTransformer.transformers()).entrySet()) {
+        identifiers.put(annotatedTransformer.withTransformers(e.getKey()), e.getValue());
+      }
+    } else if (codeTransformer instanceof RefasterRule) {
+      identifiers.put(
+          codeTransformer, extractRuleIdentifiers((RefasterRule<?, ?>) codeTransformer));
+    } else {
+      /* Unrecognized `CodeTransformer` types are indexed such that they always apply. */
+      identifiers.put(codeTransformer, ImmutableSet.of(ImmutableSet.of()));
+    }
+  }
+
+  // XXX: Consider decomposing `RefasterRule`s such that each rule has exactly one
+  // `@BeforeTemplate`.
+  private static ImmutableSet<ImmutableSet<String>> extractRuleIdentifiers(
+      RefasterRule<?, ?> refasterRule) {
+    ImmutableSet.Builder<ImmutableSet<String>> results = ImmutableSet.builder();
+
+    for (Object template : RefasterIntrospection.getBeforeTemplates(refasterRule)) {
+      if (template instanceof ExpressionTemplate expressionTemplate) {
+        UExpression expr = RefasterIntrospection.getExpression(expressionTemplate);
+        results.addAll(extractRuleIdentifiers(ImmutableList.of(expr)));
+      } else if (template instanceof BlockTemplate blockTemplate) {
+        ImmutableList<UStatement> statements =
+            RefasterIntrospection.getTemplateStatements(blockTemplate);
+        results.addAll(extractRuleIdentifiers(statements));
+      } else {
+        throw new IllegalStateException(
+            String.format("Unexpected template type '%s'", template.getClass()));
+      }
+    }
+
+    return results.build();
+  }
+
+  // XXX: Consider interning the strings (once a benchmark is in place).
+  private static ImmutableSet<ImmutableSet<String>> extractRuleIdentifiers(
+      ImmutableList<? extends Tree> trees) {
+    List<Set<String>> identifierCombinations = new ArrayList<>();
+    identifierCombinations.add(new HashSet<>());
+    TemplateIdentifierExtractor.INSTANCE.scan(trees, identifierCombinations);
+    return identifierCombinations.stream().map(ImmutableSet::copyOf).collect(toImmutableSet());
+  }
+
+  private static Set<String> extractSourceIdentifiers(Tree tree) {
+    Set<String> identifiers = new HashSet<>();
+    SourceIdentifierExtractor.INSTANCE.scan(tree, identifiers);
+    return identifiers;
+  }
+
+  /**
+   * Returns a unique string representation of the given {@link Tree.Kind}.
+   *
+   * @return A string representation of the operator, if known
+   * @throws IllegalArgumentException If the given input is not supported.
+   */
+  // XXX: Extend list to cover remaining cases; at least for any `Kind` that may appear in a
+  // Refaster template. (E.g. keywords such as `if`, `instanceof`, `new`, ...)
+  private static String treeKindToString(Tree.Kind kind) {
+    return switch (kind) {
+      case ASSIGNMENT -> "=";
+      case POSTFIX_INCREMENT -> "x++";
+      case PREFIX_INCREMENT -> "++x";
+      case POSTFIX_DECREMENT -> "x--";
+      case PREFIX_DECREMENT -> "--x";
+      case UNARY_PLUS -> "+x";
+      case UNARY_MINUS -> "-x";
+      case BITWISE_COMPLEMENT -> "~";
+      case LOGICAL_COMPLEMENT -> "!";
+      case MULTIPLY -> "*";
+      case DIVIDE -> "/";
+      case REMAINDER -> "%";
+      case PLUS -> "+";
+      case MINUS -> "-";
+      case LEFT_SHIFT -> "<<";
+      case RIGHT_SHIFT -> ">>";
+      case UNSIGNED_RIGHT_SHIFT -> ">>>";
+      case LESS_THAN -> "<";
+      case GREATER_THAN -> ">";
+      case LESS_THAN_EQUAL -> "<=";
+      case GREATER_THAN_EQUAL -> ">=";
+      case EQUAL_TO -> "==";
+      case NOT_EQUAL_TO -> "!=";
+      case AND -> "&";
+      case XOR -> "^";
+      case OR -> "|";
+      case CONDITIONAL_AND -> "&&";
+      case CONDITIONAL_OR -> "||";
+      case MULTIPLY_ASSIGNMENT -> "*=";
+      case DIVIDE_ASSIGNMENT -> "/=";
+      case REMAINDER_ASSIGNMENT -> "%=";
+      case PLUS_ASSIGNMENT -> "+=";
+      case MINUS_ASSIGNMENT -> "-=";
+      case LEFT_SHIFT_ASSIGNMENT -> "<<=";
+      case RIGHT_SHIFT_ASSIGNMENT -> ">>=";
+      case UNSIGNED_RIGHT_SHIFT_ASSIGNMENT -> ">>>=";
+      case AND_ASSIGNMENT -> "&=";
+      case XOR_ASSIGNMENT -> "^=";
+      case OR_ASSIGNMENT -> "|=";
+      default -> throw new IllegalStateException("Cannot convert Tree.Kind to a String: " + kind);
+    };
+  }
+
+  private static final class RefasterIntrospection {
+    // XXX: Update `ErrorProneRuntimeClasspath` to not suggest inaccessible types.
+    @SuppressWarnings("ErrorProneRuntimeClasspath")
+    private static final String UCLASS_IDENT_FQCN = "com.google.errorprone.refaster.UClassIdent";
+
+    private static final Class<?> UCLASS_IDENT = getClass(UCLASS_IDENT_FQCN);
+    private static final Method METHOD_REFASTER_RULE_BEFORE_TEMPLATES =
+        getMethod(RefasterRule.class, "beforeTemplates");
+    private static final Method METHOD_EXPRESSION_TEMPLATE_EXPRESSION =
+        getMethod(ExpressionTemplate.class, "expression");
+    private static final Method METHOD_BLOCK_TEMPLATE_TEMPLATE_STATEMENTS =
+        getMethod(BlockTemplate.class, "templateStatements");
+    private static final Method METHOD_USTATIC_IDENT_CLASS_IDENT =
+        getMethod(UStaticIdent.class, "classIdent");
+    private static final Method METHOD_UCLASS_IDENT_GET_TOP_LEVEL_CLASS =
+        getMethod(UCLASS_IDENT, "getTopLevelClass");
+    private static final Method METHOD_UANY_OF_EXPRESSIONS = getMethod(UAnyOf.class, "expressions");
+
+    static boolean isUClassIdent(IdentifierTree tree) {
+      return UCLASS_IDENT.isInstance(tree);
+    }
+
+    static ImmutableList<?> getBeforeTemplates(RefasterRule<?, ?> refasterRule) {
+      return invokeMethod(METHOD_REFASTER_RULE_BEFORE_TEMPLATES, refasterRule);
+    }
+
+    static UExpression getExpression(ExpressionTemplate template) {
+      return invokeMethod(METHOD_EXPRESSION_TEMPLATE_EXPRESSION, template);
+    }
+
+    static ImmutableList<UStatement> getTemplateStatements(BlockTemplate template) {
+      return invokeMethod(METHOD_BLOCK_TEMPLATE_TEMPLATE_STATEMENTS, template);
+    }
+
+    static IdentifierTree getClassIdent(UStaticIdent tree) {
+      return invokeMethod(METHOD_USTATIC_IDENT_CLASS_IDENT, tree);
+    }
+
+    // Arguments to this method must actually be of the package-private type `UClassIdent`.
+    static String getTopLevelClass(IdentifierTree uClassIdent) {
+      return invokeMethod(METHOD_UCLASS_IDENT_GET_TOP_LEVEL_CLASS, uClassIdent);
+    }
+
+    static ImmutableList<UExpression> getExpressions(UAnyOf tree) {
+      return invokeMethod(METHOD_UANY_OF_EXPRESSIONS, tree);
+    }
+
+    private static Class<?> getClass(String fqcn) {
+      try {
+        return RefasterIntrospection.class.getClassLoader().loadClass(fqcn);
+      } catch (ClassNotFoundException e) {
+        throw new IllegalStateException(String.format("Failed to load class `%s`", fqcn), e);
+      }
+    }
+
+    private static Method getMethod(Class<?> clazz, String methodName) {
+      try {
+        Method method = clazz.getDeclaredMethod(methodName);
+        method.setAccessible(true);
+        return method;
+      } catch (NoSuchMethodException e) {
+        throw new IllegalStateException(
+            String.format("No method `%s` on class `%s`", methodName, clazz.getName()), e);
+      }
+    }
+
+    @SuppressWarnings({"TypeParameterUnusedInFormals", "unchecked"})
+    private static <T> T invokeMethod(Method method, Object instance) {
+      try {
+        return (T) method.invoke(instance);
+      } catch (IllegalAccessException | InvocationTargetException e) {
+        throw new IllegalStateException(String.format("Failed to invoke method `%s`", method), e);
+      }
+    }
+  }
+
+  private static final class TemplateIdentifierExtractor
+      extends TreeScanner<@Nullable Void, List<Set<String>>> {
+    private static final TemplateIdentifierExtractor INSTANCE = new TemplateIdentifierExtractor();
+
+    @Override
+    public @Nullable Void visitIdentifier(
+        IdentifierTree node, List<Set<String>> identifierCombinations) {
+      // XXX: Also include the package name if not `java.lang`; it must be present.
+      if (RefasterIntrospection.isUClassIdent(node)) {
+        for (Set<String> ids : identifierCombinations) {
+          ids.add(getSimpleName(RefasterIntrospection.getTopLevelClass(node)));
+          ids.add(getIdentifier(node));
+        }
+      } else if (node instanceof UStaticIdent uStaticIdent) {
+        IdentifierTree subNode = RefasterIntrospection.getClassIdent(uStaticIdent);
+        for (Set<String> ids : identifierCombinations) {
+          ids.add(getSimpleName(RefasterIntrospection.getTopLevelClass(subNode)));
+          ids.add(getIdentifier(subNode));
+          ids.add(node.getName().toString());
+        }
+      }
+
+      return null;
+    }
+
+    private static String getIdentifier(IdentifierTree tree) {
+      return getSimpleName(tree.getName().toString());
+    }
+
+    private static String getSimpleName(String fqcn) {
+      int index = fqcn.lastIndexOf('.');
+      return index < 0 ? fqcn : fqcn.substring(index + 1);
+    }
+
+    @Override
+    public @Nullable Void visitMemberReference(
+        MemberReferenceTree node, List<Set<String>> identifierCombinations) {
+      super.visitMemberReference(node, identifierCombinations);
+      String id = node.getName().toString();
+      identifierCombinations.forEach(ids -> ids.add(id));
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitMemberSelect(
+        MemberSelectTree node, List<Set<String>> identifierCombinations) {
+      super.visitMemberSelect(node, identifierCombinations);
+      String id = node.getIdentifier().toString();
+      identifierCombinations.forEach(ids -> ids.add(id));
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitAssignment(
+        AssignmentTree node, List<Set<String>> identifierCombinations) {
+      registerOperator(node, identifierCombinations);
+      return super.visitAssignment(node, identifierCombinations);
+    }
+
+    @Override
+    public @Nullable Void visitCompoundAssignment(
+        CompoundAssignmentTree node, List<Set<String>> identifierCombinations) {
+      registerOperator(node, identifierCombinations);
+      return super.visitCompoundAssignment(node, identifierCombinations);
+    }
+
+    @Override
+    public @Nullable Void visitUnary(UnaryTree node, List<Set<String>> identifierCombinations) {
+      registerOperator(node, identifierCombinations);
+      return super.visitUnary(node, identifierCombinations);
+    }
+
+    @Override
+    public @Nullable Void visitBinary(BinaryTree node, List<Set<String>> identifierCombinations) {
+      registerOperator(node, identifierCombinations);
+      return super.visitBinary(node, identifierCombinations);
+    }
+
+    private static void registerOperator(
+        ExpressionTree node, List<Set<String>> identifierCombinations) {
+      String id = treeKindToString(node.getKind());
+      identifierCombinations.forEach(ids -> ids.add(id));
+    }
+
+    @Override
+    public @Nullable Void visitOther(Tree node, List<Set<String>> identifierCombinations) {
+      if (node instanceof UAnyOf uAnyOf) {
+        List<Set<String>> base = copy(identifierCombinations);
+        identifierCombinations.clear();
+
+        for (UExpression expr : RefasterIntrospection.getExpressions(uAnyOf)) {
+          List<Set<String>> branch = copy(base);
+          scan(expr, branch);
+          identifierCombinations.addAll(branch);
+        }
+      }
+
+      return null;
+    }
+
+    private static List<Set<String>> copy(List<Set<String>> identifierCombinations) {
+      return identifierCombinations.stream()
+          .map(HashSet::new)
+          .collect(toCollection(ArrayList::new));
+    }
+  }
+
+  private static final class SourceIdentifierExtractor
+      extends TreeScanner<@Nullable Void, Set<String>> {
+    private static final SourceIdentifierExtractor INSTANCE = new SourceIdentifierExtractor();
+
+    @Override
+    public @Nullable Void visitPackage(PackageTree node, Set<String> identifiers) {
+      /* Refaster rules never match package declarations. */
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitClass(ClassTree node, Set<String> identifiers) {
+      /*
+       * Syntactic details of a class declaration other than the definition of its members do not
+       * need to be reflected in a Refaster rule for it to apply to the class's code.
+       */
+      return scan(node.getMembers(), identifiers);
+    }
+
+    @Override
+    public @Nullable Void visitMethod(MethodTree node, Set<String> identifiers) {
+      /*
+       * Syntactic details of a method declaration other than its body do not need to be reflected
+       * in a Refaster rule for it to apply to the method's code.
+       */
+      return scan(node.getBody(), identifiers);
+    }
+
+    @Override
+    public @Nullable Void visitVariable(VariableTree node, Set<String> identifiers) {
+      /* A variable's modifiers and name do not influence where a Refaster rule matches. */
+      return reduce(scan(node.getInitializer(), identifiers), scan(node.getType(), identifiers));
+    }
+
+    @Override
+    public @Nullable Void visitIdentifier(IdentifierTree node, Set<String> identifiers) {
+      identifiers.add(node.getName().toString());
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitMemberReference(MemberReferenceTree node, Set<String> identifiers) {
+      super.visitMemberReference(node, identifiers);
+      identifiers.add(node.getName().toString());
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitMemberSelect(MemberSelectTree node, Set<String> identifiers) {
+      super.visitMemberSelect(node, identifiers);
+      identifiers.add(node.getIdentifier().toString());
+      return null;
+    }
+
+    @Override
+    public @Nullable Void visitAssignment(AssignmentTree node, Set<String> identifiers) {
+      registerOperator(node, identifiers);
+      return super.visitAssignment(node, identifiers);
+    }
+
+    @Override
+    public @Nullable Void visitCompoundAssignment(
+        CompoundAssignmentTree node, Set<String> identifiers) {
+      registerOperator(node, identifiers);
+      return super.visitCompoundAssignment(node, identifiers);
+    }
+
+    @Override
+    public @Nullable Void visitUnary(UnaryTree node, Set<String> identifiers) {
+      registerOperator(node, identifiers);
+      return super.visitUnary(node, identifiers);
+    }
+
+    @Override
+    public @Nullable Void visitBinary(BinaryTree node, Set<String> identifiers) {
+      registerOperator(node, identifiers);
+      return super.visitBinary(node, identifiers);
+    }
+
+    private static void registerOperator(ExpressionTree node, Set<String> identifiers) {
+      identifiers.add(treeKindToString(node.getKind()));
+    }
+  }
+}

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

@@ -0,0 +1,83 @@
+package tech.picnic.errorprone.refaster.runner;
+
+import static com.google.common.collect.ImmutableListMultimap.flatteningToImmutableListMultimap;
+import static java.util.function.Function.identity;
+
+import com.google.common.collect.ImmutableListMultimap;
+import com.jakewharton.nopen.annotation.Open;
+import java.util.Collection;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+import tech.picnic.errorprone.refaster.runner.NodeTestCase.NodeTestCaseEntry;
+
+@Open
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Fork(jvmArgs = {"-Xms1G", "-Xmx1G"})
+@Warmup(iterations = 5)
+@Measurement(iterations = 10)
+public class NodeBenchmark {
+  @SuppressWarnings("NullAway" /* Initialized by `@Setup` method. */)
+  private ImmutableListMultimap<NodeTestCase<Integer>, NodeTestCaseEntry<Integer>> testCases;
+
+  public static void main(String[] args) throws RunnerException {
+    // XXX: Update `ErrorProneRuntimeClasspath` to allow same-package `Class` references.
+    @SuppressWarnings("ErrorProneRuntimeClasspath")
+    String testRegex = Pattern.quote(NodeBenchmark.class.getCanonicalName());
+    new Runner(new OptionsBuilder().include(testRegex).forks(1).build()).run();
+  }
+
+  @Setup
+  public final void setUp() {
+    Random random = new Random(0);
+
+    testCases =
+        Stream.of(
+                NodeTestCase.generate(100, 5, 10, 10, random),
+                NodeTestCase.generate(100, 5, 10, 100, random),
+                NodeTestCase.generate(100, 5, 10, 1000, random),
+                NodeTestCase.generate(1000, 10, 20, 10, random),
+                NodeTestCase.generate(1000, 10, 20, 100, random),
+                NodeTestCase.generate(1000, 10, 20, 1000, random),
+                NodeTestCase.generate(1000, 10, 20, 10000, random))
+            .collect(
+                flatteningToImmutableListMultimap(
+                    identity(), testCase -> testCase.generateTestCaseEntries(random)));
+  }
+
+  @Benchmark
+  public final void create(Blackhole bh) {
+    for (NodeTestCase<Integer> testCase : testCases.keySet()) {
+      bh.consume(testCase.buildTree());
+    }
+  }
+
+  @Benchmark
+  public final void collectReachableValues(Blackhole bh) {
+    for (Map.Entry<NodeTestCase<Integer>, Collection<NodeTestCaseEntry<Integer>>> e :
+        testCases.asMap().entrySet()) {
+      Node<Integer> tree = e.getKey().buildTree();
+      for (NodeTestCaseEntry<Integer> testCaseEntry : e.getValue()) {
+        tree.collectReachableValues(testCaseEntry.candidateEdges(), bh::consume);
+      }
+    }
+  }
+}

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

@@ -0,0 +1,47 @@
+package tech.picnic.errorprone.refaster.runner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Random;
+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 NodeTest {
+  private static Stream<Arguments> collectReachableValuesTestCases() {
+    Random random = new Random(0);
+
+    return Stream.of(
+            NodeTestCase.generate(0, 0, 0, 0, random),
+            NodeTestCase.generate(1, 1, 1, 1, random),
+            NodeTestCase.generate(2, 2, 2, 10, random),
+            NodeTestCase.generate(10, 2, 5, 10, random),
+            NodeTestCase.generate(10, 2, 5, 100, random),
+            NodeTestCase.generate(100, 5, 10, 100, random),
+            NodeTestCase.generate(100, 5, 10, 1000, random))
+        .flatMap(
+            testCase -> {
+              Node<Integer> tree = testCase.buildTree();
+              return testCase
+                  .generateTestCaseEntries(random)
+                  .map(e -> arguments(tree, e.candidateEdges(), e.reachableValues()));
+            });
+  }
+
+  @MethodSource("collectReachableValuesTestCases")
+  @ParameterizedTest
+  void collectReachableValues(
+      Node<Integer> tree,
+      ImmutableSet<String> candidateEdges,
+      Collection<Integer> expectedReachable) {
+    List<Integer> actualReachable = new ArrayList<>();
+    tree.collectReachableValues(candidateEdges, actualReachable::add);
+    assertThat(actualReachable).hasSameElementsAs(expectedReachable);
+  }
+}

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

@@ -0,0 +1,140 @@
+package tech.picnic.errorprone.refaster.runner;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+import static com.google.common.collect.ImmutableSetMultimap.flatteningToImmutableSetMultimap;
+import static java.util.function.Function.identity;
+import static java.util.stream.Collectors.collectingAndThen;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableCollection;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSetMultimap;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Random;
+import java.util.stream.Stream;
+
+@AutoValue
+abstract class NodeTestCase<V> {
+  static NodeTestCase<Integer> generate(
+      int entryCount, int maxPathCount, int maxPathLength, int pathValueDomainSize, Random random) {
+    return random
+        .ints(entryCount)
+        .boxed()
+        .collect(
+            collectingAndThen(
+                flatteningToImmutableSetMultimap(
+                    identity(),
+                    i ->
+                        random
+                            .ints(random.nextInt(maxPathCount + 1))
+                            .mapToObj(
+                                p ->
+                                    random
+                                        .ints(
+                                            random.nextInt(maxPathLength + 1),
+                                            0,
+                                            pathValueDomainSize)
+                                        .mapToObj(String::valueOf)
+                                        .collect(toImmutableSet()))),
+                AutoValue_NodeTestCase::new));
+  }
+
+  abstract ImmutableSetMultimap<V, ImmutableSet<String>> input();
+
+  final Node<V> buildTree() {
+    return Node.create(input().keySet(), input()::get);
+  }
+
+  final Stream<NodeTestCaseEntry<V>> generateTestCaseEntries(Random random) {
+    return generatePathTestCases(input(), random);
+  }
+
+  private static <V> Stream<NodeTestCaseEntry<V>> generatePathTestCases(
+      ImmutableSetMultimap<V, ImmutableSet<String>> treeInput, Random random) {
+    ImmutableSet<String> allEdges =
+        treeInput.values().stream().flatMap(ImmutableSet::stream).collect(toImmutableSet());
+
+    return Stream.concat(
+            Stream.of(ImmutableSet.<String>of()), shuffle(treeInput.values(), random).stream())
+        // XXX: Use `random.nextInt(20, 100)` once we no longer target JDK 11. (And consider
+        // introducing a Refaster template for this case.)
+        .limit(20 + random.nextInt(80))
+        .flatMap(edges -> generateVariations(edges, allEdges, "unused", random))
+        .distinct()
+        .map(edges -> createTestCaseEntry(treeInput, edges));
+  }
+
+  private static <T> Stream<ImmutableSet<T>> generateVariations(
+      ImmutableSet<T> baseEdges, ImmutableSet<T> allEdges, T unusedEdge, Random random) {
+    Optional<T> knownEdge = selectRandomElement(allEdges, random);
+
+    return Stream.of(
+            random.nextBoolean() ? null : baseEdges,
+            random.nextBoolean() ? null : shuffle(baseEdges, random),
+            random.nextBoolean() ? null : insertValue(baseEdges, unusedEdge, random),
+            baseEdges.isEmpty() || random.nextBoolean()
+                ? null
+                : randomStrictSubset(baseEdges, random),
+            baseEdges.isEmpty() || random.nextBoolean()
+                ? null
+                : insertValue(randomStrictSubset(baseEdges, random), unusedEdge, random),
+            baseEdges.isEmpty() || random.nextBoolean()
+                ? null
+                : knownEdge
+                    .map(edge -> insertValue(randomStrictSubset(baseEdges, random), edge, random))
+                    .orElse(null))
+        .filter(Objects::nonNull);
+  }
+
+  private static <T> Optional<T> selectRandomElement(ImmutableSet<T> collection, Random random) {
+    return collection.isEmpty()
+        ? Optional.empty()
+        : Optional.of(collection.asList().get(random.nextInt(collection.size())));
+  }
+
+  private static <T> ImmutableSet<T> shuffle(ImmutableCollection<T> values, Random random) {
+    List<T> allValues = new ArrayList<>(values);
+    Collections.shuffle(allValues, random);
+    return ImmutableSet.copyOf(allValues);
+  }
+
+  private static <T> ImmutableSet<T> insertValue(
+      ImmutableSet<T> values, T extraValue, Random random) {
+    List<T> allValues = new ArrayList<>(values);
+    allValues.add(random.nextInt(values.size() + 1), extraValue);
+    return ImmutableSet.copyOf(allValues);
+  }
+
+  private static <T> ImmutableSet<T> randomStrictSubset(ImmutableSet<T> values, Random random) {
+    checkArgument(!values.isEmpty(), "Cannot select strict subset of random collection");
+
+    List<T> allValues = new ArrayList<>(values);
+    Collections.shuffle(allValues, random);
+    return ImmutableSet.copyOf(allValues.subList(0, random.nextInt(allValues.size())));
+  }
+
+  private static <V> NodeTestCaseEntry<V> createTestCaseEntry(
+      ImmutableSetMultimap<V, ImmutableSet<String>> treeInput, ImmutableSet<String> edges) {
+    return new AutoValue_NodeTestCase_NodeTestCaseEntry<>(
+        edges,
+        treeInput.asMap().entrySet().stream()
+            .filter(e -> e.getValue().stream().anyMatch(edges::containsAll))
+            .map(Map.Entry::getKey)
+            .collect(toImmutableList()));
+  }
+
+  @AutoValue
+  abstract static class NodeTestCaseEntry<V> {
+    abstract ImmutableSet<String> candidateEdges();
+
+    abstract ImmutableList<V> reachableValues();
+  }
+}

refaster-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-support</artifactId>

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

@@ -46,7 +46,12 @@ public abstract class AnnotatedCompositeCodeTransformer implements CodeTransform
 
   abstract String packageName();
 
-  abstract ImmutableList<CodeTransformer> transformers();
+  /**
+   * Return The {@link CodeTransformer}s to which to delegate.
+   *
+   * @return The ordered {@link CodeTransformer}s to which to delegate.
+   */
+  public abstract ImmutableList<CodeTransformer> transformers();
 
   @Override
   @SuppressWarnings("java:S3038" /* All AutoValue properties must be specified explicitly. */)
@@ -67,6 +72,18 @@ public abstract class AnnotatedCompositeCodeTransformer implements CodeTransform
     return new AutoValue_AnnotatedCompositeCodeTransformer(packageName, transformers, annotations);
   }
 
+  /**
+   * Returns a new {@link AnnotatedCompositeCodeTransformer} similar to this one, but with the
+   * specified transformers.
+   *
+   * @param transformers The replacement transformers.
+   * @return A derivative {@link AnnotatedCompositeCodeTransformer}.
+   */
+  public AnnotatedCompositeCodeTransformer withTransformers(CodeTransformer... transformers) {
+    return new AutoValue_AnnotatedCompositeCodeTransformer(
+        packageName(), ImmutableList.copyOf(transformers), annotations());
+  }
+
   @Override
   public final void apply(TreePath path, Context context, DescriptionListener listener) {
     for (CodeTransformer transformer : transformers()) {

refaster-test-support/pom.xml

@@ -5,7 +5,7 @@
     <parent>
         <groupId>tech.picnic.error-prone-support</groupId>
         <artifactId>error-prone-support</artifactId>
-        <version>0.22.0</version>
+        <version>0.21.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>refaster-test-support</artifactId>

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

@@ -0,0 +1,31 @@
+package tech.picnic.errorprone.refaster.test;
+
+import static java.util.Collections.singletonMap;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.refaster.Refaster;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.AbstractMap.SimpleImmutableEntry;
+import java.util.Map;
+
+/** Refaster rule collection to validate the reporting of missing test methods. */
+final class NestedRefasterAnyOfRules {
+  private NestedRefasterAnyOfRules() {}
+
+  static final class NestedRefasterAnyOf<K, V> {
+    @BeforeTemplate
+    @SuppressWarnings({"ImmutableMapOf1", "MapEntry"} /* Similar rules for testing purposes. */)
+    Map<K, V> before(K k1, V v1) {
+      return Refaster.anyOf(
+          ImmutableMap.ofEntries(
+              Refaster.anyOf(Map.entry(k1, v1), new SimpleImmutableEntry<>(k1, v1))),
+          singletonMap(k1, v1));
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1) {
+      return ImmutableMap.of(k1, v1);
+    }
+  }
+}

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

@@ -21,8 +21,10 @@ final class RefasterRuleCollectionTest {
         MethodWithoutPrefixRules.class,
         MisnamedTestClassRules.class,
         MissingTestAndWrongTestRules.class,
+        NestedRefasterAnyOfRules.class,
         PartialTestMatchRules.class,
         RuleWithoutTestRules.class,
+        SingleRefasterAnyOfRules.class,
         ValidRules.class
       })
   void verifyRefasterRuleCollections(Class<?> clazz) {

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

@@ -0,0 +1,27 @@
+package tech.picnic.errorprone.refaster.test;
+
+import static java.util.Collections.singletonMap;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.refaster.Refaster;
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.Map;
+
+/** Refaster rule collection to validate the reporting of missing test methods. */
+final class SingleRefasterAnyOfRules {
+  private SingleRefasterAnyOfRules() {}
+
+  static final class SingleRefasterAnyOf<K, V> {
+    @BeforeTemplate
+    @SuppressWarnings("ImmutableMapOf1" /* Similar rule for testing purposes. */)
+    Map<K, V> before(K k1, V v1) {
+      return Refaster.anyOf(ImmutableMap.ofEntries(Map.entry(k1, v1)), singletonMap(k1, v1));
+    }
+
+    @AfterTemplate
+    ImmutableMap<K, V> after(K k1, V v1) {
+      return ImmutableMap.of(k1, v1);
+    }
+  }
+}

refaster-test-support/src/test/resources/tech/picnic/errorprone/refaster/test/NestedRefasterAnyOfRulesTestInput.java

@@ -0,0 +1,12 @@
+package tech.picnic.errorprone.refaster.test;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.Map;
+
+/** Code to test the Refaster rules from {@link NestedRefasterAnyOfRules}. */
+final class NestedRefasterAnyOfRulesTest implements RefasterRuleCollectionTestCase {
+  Map<?, ?> testNestedRefasterAnyOf() {
+    Map<String, String> stringStringMap = Map.of("1", "2");
+    return ImmutableMap.ofEntries(Map.entry("k1", "v1"));
+  }
+}

refaster-test-support/src/test/resources/tech/picnic/errorprone/refaster/test/NestedRefasterAnyOfRulesTestOutput.java

@@ -0,0 +1,12 @@
+package tech.picnic.errorprone.refaster.test;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.Map;
+
+/** Code to test the Refaster rules from {@link NestedRefasterAnyOfRules}. */
+final class NestedRefasterAnyOfRulesTest implements RefasterRuleCollectionTestCase {
+  Map<?, ?> testNestedRefasterAnyOf() {
+    Map<String, String> stringStringMap = Map.of("1", "2");
+    return ImmutableMap.of("k1", "v1");
+  }
+}

refaster-test-support/src/test/resources/tech/picnic/errorprone/refaster/test/SingleRefasterAnyOfRulesTestInput.java

@@ -0,0 +1,17 @@
+package tech.picnic.errorprone.refaster.test;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.Collections;
+import java.util.Map;
+
+/** Code to test the Refaster rules from {@link SingleRefasterAnyOfRules}. */
+final class SingleRefasterAnyOfRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Collections.class);
+  }
+
+  Map<?, ?> testSingleRefasterAnyOf() {
+    return Collections.singletonMap("k1", "v1");
+  }
+}

refaster-test-support/src/test/resources/tech/picnic/errorprone/refaster/test/SingleRefasterAnyOfRulesTestOutput.java

@@ -0,0 +1,18 @@
+package tech.picnic.errorprone.refaster.test;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import java.util.Collections;
+import java.util.Map;
+
+/** Code to test the Refaster rules from {@link SingleRefasterAnyOfRules}. */
+final class SingleRefasterAnyOfRulesTest implements RefasterRuleCollectionTestCase {
+  @Override
+  public ImmutableSet<Object> elidedTypesAndStaticImports() {
+    return ImmutableSet.of(Collections.class);
+  }
+
+  Map<?, ?> testSingleRefasterAnyOf() {
+    return ImmutableMap.of("k1", "v1");
+  }
+}