Fix analysis performance regression caused by header compilation

When building --direct_dependency/--indirect_dependency args, use a set for the
direct jars to avoid an O(n) contains check, and make the CustomMultiArgv class
static to avoid a memory leak. Also avoid flattening the NestedSet of direct
jars for as long as possible.

--
MOS_MIGRATED_REVID=125468789

6 files changed, 93 insertions, 103 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
index 870cee733a..edc438dbb3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
@@ -375,8 +375,9 @@ public class AndroidCommon {
       ImmutableList.Builder<Artifact> jarsProducedForRuntime) throws InterruptedException {
     compileResourceJar(javaSemantics, resourcesJar);
     // Add the compiled resource jar to the classpath of the main compilation.
-    attributes.addDirectJars(ImmutableList.of(resourceClassJar));
-    attributes.addDirectCompileTimeClassPathEntries(ImmutableList.of(resourceClassJar));
+    NestedSet<Artifact> directJars = NestedSetBuilder.create(Order.STABLE_ORDER, resourceClassJar);
+    attributes.addDirectJars(directJars);
+    attributes.addCompileTimeClassPathEntries(directJars);
     // Add the compiled resource jar to the classpath of consuming targets.
     artifactsBuilder.addCompileTimeJar(resourceClassJar);
     // Combined resource constants needs to come even before our own classes that may contain
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompilationHelper.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompilationHelper.java
index e4f654b941..84fd903601 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompilationHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompilationHelper.java
@@ -157,7 +157,7 @@ public final class JavaCompilationHelper extends BaseJavaCompilationHelper {
     builder.addProcessorPaths(attributes.getProcessorPath());
     builder.addProcessorNames(attributes.getProcessorNames());
     builder.setStrictJavaDeps(attributes.getStrictJavaDeps());
-    builder.addDirectJars(attributes.getDirectJars());
+    builder.setDirectJars(attributes.getDirectJars());
     builder.addCompileTimeDependencyArtifacts(attributes.getCompileTimeDependencyArtifacts());
     builder.setRuleKind(attributes.getRuleKind());
     builder.setTargetLabel(attributes.getTargetLabel());
@@ -279,7 +279,7 @@ public final class JavaCompilationHelper extends BaseJavaCompilationHelper {
     builder.setOutputDepsProto(headerDeps);
     builder.setStrictJavaDeps(attributes.getStrictJavaDeps());
     builder.addCompileTimeDependencyArtifacts(attributes.getCompileTimeDependencyArtifacts());
-    builder.addDirectJars(attributes.getDirectJars());
+    builder.setDirectJars(attributes.getDirectJars());
     builder.setRuleKind(attributes.getRuleKind());
     builder.setTargetLabel(attributes.getTargetLabel());
     builder.setJavaBaseInputs(getHostJavabaseInputsNonStatic(ruleContext));
@@ -521,10 +521,11 @@ public final class JavaCompilationHelper extends BaseJavaCompilationHelper {
     return jar;
   }
 
-  private void addArgsAndJarsToAttributes(JavaCompilationArgs args, Iterable<Artifact> directJars) {
+  private void addArgsAndJarsToAttributes(
+      JavaCompilationArgs args, NestedSet<Artifact> directJars) {
     // Can only be non-null when isStrict() returns true.
     if (directJars != null) {
-      attributes.addDirectCompileTimeClassPathEntries(directJars);
+      attributes.addCompileTimeClassPathEntries(directJars);
       attributes.addDirectJars(directJars);
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileAction.java
index 5c3d36d41e..c9abbda252 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileAction.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.rules.java;
 
+import static com.google.devtools.build.lib.util.Preconditions.checkNotNull;
 import static java.nio.charset.StandardCharsets.ISO_8859_1;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -68,6 +69,7 @@ import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Action that represents a Java compilation.
@@ -144,10 +146,8 @@ public final class JavaCompileAction extends AbstractAction {
    */
   private final ImmutableList<String> javacOpts;
 
-  /**
-   * The subset of classpath jars provided by direct dependencies.
-   */
-  private final ImmutableList<Artifact> directJars;
+  /** The subset of classpath jars provided by direct dependencies. */
+  private final NestedSet<Artifact> directJars;
 
   /**
    * The level of strict dependency checks (off, warnings, or errors).
@@ -163,12 +163,12 @@ public final class JavaCompileAction extends AbstractAction {
    * Constructs an action to compile a set of Java source files to class files.
    *
    * @param owner the action owner, typically a java_* RuleConfiguredTarget.
-   * @param baseInputs the set of the input artifacts of the compile action
-   *        without the parameter file action;
+   * @param baseInputs the set of the input artifacts of the compile action without the parameter
+   *     file action;
    * @param outputs the outputs of the action
-   * @param javaCompileCommandLine the command line for the java library
-   *        builder - it's actually written to the parameter file, but other
-   *        parts (for example, ide_build_info) need access to the data
+   * @param javaCompileCommandLine the command line for the java library builder - it's actually
+   *     written to the parameter file, but other parts (for example, ide_build_info) need access to
+   *     the data
    * @param commandLine the actual invocation command line
    */
   private JavaCompileAction(
@@ -191,7 +191,7 @@ public final class JavaCompileAction extends AbstractAction {
       Collection<Artifact> sourceJars,
       Collection<Artifact> sourceFiles,
       List<String> javacOpts,
-      Collection<Artifact> directJars,
+      NestedSet<Artifact> directJars,
       BuildConfiguration.StrictDepsMode strictJavaDeps,
       Collection<Artifact> compileTimeDependencyArtifacts) {
     super(
@@ -213,7 +213,7 @@ public final class JavaCompileAction extends AbstractAction {
     this.javaCompileCommandLine = javaCompileCommandLine;
     this.commandLine = commandLine;
 
-    this.classDirectory = Preconditions.checkNotNull(classDirectory);
+    this.classDirectory = checkNotNull(classDirectory);
     this.outputJar = outputJar;
     this.classpathEntries = classpathEntries;
     this.bootclasspathEntries = ImmutableList.copyOf(bootclasspathEntries);
@@ -226,7 +226,7 @@ public final class JavaCompileAction extends AbstractAction {
     this.sourceJars = ImmutableList.copyOf(sourceJars);
     this.sourceFiles = ImmutableList.copyOf(sourceFiles);
     this.javacOpts = ImmutableList.copyOf(javacOpts);
-    this.directJars = ImmutableList.copyOf(directJars);
+    this.directJars = checkNotNull(directJars, "directJars must not be null");
     this.strictJavaDeps = strictJavaDeps;
     this.compileTimeDependencyArtifacts = ImmutableList.copyOf(compileTimeDependencyArtifacts);
   }
@@ -292,7 +292,7 @@ public final class JavaCompileAction extends AbstractAction {
   }
 
   @VisibleForTesting
-  public Collection<Artifact> getDirectJars() {
+  public NestedSet<Artifact> getDirectJars() {
     return directJars;
   }
 
@@ -472,13 +472,13 @@ public final class JavaCompileAction extends AbstractAction {
    * Creates an instance.
    *
    * @param configuration the build configuration, which provides the default options and the path
-   *        to the compiler, etc.
+   *     to the compiler, etc.
    * @param classDirectory the directory in which generated classfiles are placed relative to the
-   *        exec root
+   *     exec root
    * @param sourceGenDirectory the directory where source files generated by annotation processors
-   *        should be stored.
+   *     should be stored.
    * @param tempDirectory a directory in which the library builder can store temporary files
-   *        relative to the exec root
+   *     relative to the exec root
    * @param outputJar output jar
    * @param compressJar if true compress the output jar
    * @param outputDepsProto the proto file capturing dependency information
@@ -513,13 +513,13 @@ public final class JavaCompileAction extends AbstractAction {
       Collection<Artifact> sourceFiles,
       Collection<Artifact> extdirInputs,
       List<String> javacOpts,
-      final Collection<Artifact> directJars,
+      final NestedSet<Artifact> directJars,
       BuildConfiguration.StrictDepsMode strictJavaDeps,
       Collection<Artifact> compileTimeDependencyArtifacts,
       String ruleKind,
       Label targetLabel) {
-    Preconditions.checkNotNull(classDirectory);
-    Preconditions.checkNotNull(tempDirectory);
+    checkNotNull(classDirectory);
+    checkNotNull(tempDirectory);
 
     CustomCommandLine.Builder result = CustomCommandLine.builder();
 
@@ -615,12 +615,7 @@ public final class JavaCompileAction extends AbstractAction {
     if (strictJavaDeps != BuildConfiguration.StrictDepsMode.OFF) {
       result.add("--strict_java_deps");
       result.add(strictJavaDeps.toString());
-      result.add(new CustomMultiArgv() {
-        @Override
-        public Iterable<String> argv() {
-          return addJarsToTargets(classpath, directJars);
-        }
-      });
+      result.add(new JarsToTargetsArgv(classpath, directJars));
 
       if (configuration.getFragment(JavaConfiguration.class).getReduceJavaClasspath()
           == JavaClasspathMode.JAVABUILDER) {
@@ -673,26 +668,34 @@ public final class JavaCompileAction extends AbstractAction {
   }
 
   /**
-   * Builds the list of mappings between jars on the classpath and their
-   * originating targets names.
+   * Builds the list of mappings between jars on the classpath and their originating targets names.
    */
-  static ImmutableList<String> addJarsToTargets(
-      NestedSet<Artifact> classpath, Collection<Artifact> directJars) {
-    ImmutableList.Builder<String> builder = ImmutableList.builder();
-    for (Artifact jar : classpath) {
-      builder.add(directJars.contains(jar)
-          ? "--direct_dependency"
-          : "--indirect_dependency");
-      builder.add(jar.getExecPathString());
-      Label label = getTargetName(jar);
-      builder.add(
-          label.getPackageIdentifier().getRepository().isDefault()
-              || label.getPackageIdentifier().getRepository().isMain()
-              ? label.toString()
-              // Escape '@' prefix for .params file.
-              : "@" + label);
+  static class JarsToTargetsArgv extends CustomMultiArgv {
+    private final NestedSet<Artifact> classpath;
+    private final NestedSet<Artifact> directJars;
+
+    JarsToTargetsArgv(NestedSet<Artifact> classpath, NestedSet<Artifact> directJars) {
+      this.classpath = classpath;
+      this.directJars = directJars;
+    }
+
+    @Override
+    public Iterable<String> argv() {
+      Set<Artifact> directJarSet = directJars.toSet();
+      ImmutableList.Builder<String> builder = ImmutableList.builder();
+      for (Artifact jar : classpath) {
+        builder.add(directJarSet.contains(jar) ? "--direct_dependency" : "--indirect_dependency");
+        builder.add(jar.getExecPathString());
+        Label label = getTargetName(jar);
+        builder.add(
+            label.getPackageIdentifier().getRepository().isDefault()
+                    || label.getPackageIdentifier().getRepository().isMain()
+                ? label.toString()
+                // Escape '@' prefix for .params file.
+                : "@" + label);
+      }
+      return builder.build();
     }
-    return builder.build();
   }
 
   /**
@@ -702,7 +705,7 @@ public final class JavaCompileAction extends AbstractAction {
    * libraries), there is no generating action, so we just return the jar name in label form.
    */
   private static Label getTargetName(Artifact jar) {
-    return Preconditions.checkNotNull(jar.getOwner(), jar);
+    return checkNotNull(jar.getOwner(), jar);
   }
 
   /**
@@ -712,8 +715,8 @@ public final class JavaCompileAction extends AbstractAction {
       Artifact langtoolsJar, ImmutableList<Artifact> instrumentationJars, Artifact paramFile,
       ImmutableList<String> javaBuilderJvmFlags, String javaBuilderMainClass,
       String pathDelimiter) {
-    Preconditions.checkNotNull(langtoolsJar);
-    Preconditions.checkNotNull(javaBuilderJar);
+    checkNotNull(langtoolsJar);
+    checkNotNull(javaBuilderJar);
 
     CustomCommandLine.Builder builder =  CustomCommandLine.builder()
         .addPath(javaExecutable)
@@ -786,7 +789,7 @@ public final class JavaCompileAction extends AbstractAction {
     private final Collection<Artifact> translations = new LinkedHashSet<>();
     private BuildConfiguration.StrictDepsMode strictJavaDeps =
         BuildConfiguration.StrictDepsMode.OFF;
-    private final Collection<Artifact> directJars = new ArrayList<>();
+    private NestedSet<Artifact> directJars = NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER);
     private final Collection<Artifact> compileTimeDependencyArtifacts = new ArrayList<>();
     private List<String> javacOpts = new ArrayList<>();
     private ImmutableList<String> javacJvmOpts = ImmutableList.of();
@@ -855,7 +858,7 @@ public final class JavaCompileAction extends AbstractAction {
       // Invariant: if strictJavaDeps is OFF, then directJars and
       // dependencyArtifacts are ignored
       if (strictJavaDeps == BuildConfiguration.StrictDepsMode.OFF) {
-        directJars.clear();
+        directJars = NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER);
         compileTimeDependencyArtifacts.clear();
       }
 
@@ -1044,11 +1047,9 @@ public final class JavaCompileAction extends AbstractAction {
       return this;
     }
 
-    /**
-     * Accumulates the given jar artifacts as being provided by direct dependencies.
-     */
-    public Builder addDirectJars(Collection<Artifact> directJars) {
-      this.directJars.addAll(directJars);
+    /** Accumulates the given jar artifacts as being provided by direct dependencies. */
+    public Builder setDirectJars(NestedSet<Artifact> directJars) {
+      this.directJars = checkNotNull(directJars, "directJars must not be null");
       return this;
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
index 2dfe4a6ed9..895d1b63b5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
@@ -24,7 +24,6 @@ import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.actions.CommandLine;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
-import com.google.devtools.build.lib.analysis.actions.CustomCommandLine.CustomMultiArgv;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode;
@@ -71,7 +70,7 @@ public class JavaHeaderCompileActionBuilder {
   @Nullable private Label targetLabel;
   private PathFragment tempDirectory;
   private BuildConfiguration.StrictDepsMode strictJavaDeps = BuildConfiguration.StrictDepsMode.OFF;
-  private List<Artifact> directJars = new ArrayList<>();
+  private NestedSet<Artifact> directJars = NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER);
   private List<Artifact> compileTimeDependencyArtifacts = new ArrayList<>();
   private ImmutableList<String> javacOpts;
   private List<Artifact> processorPath = new ArrayList<>();
@@ -92,9 +91,9 @@ public class JavaHeaderCompileActionBuilder {
   }
 
   /** Sets the direct dependency artifacts. */
-  public JavaHeaderCompileActionBuilder addDirectJars(Collection<Artifact> directJars) {
+  public JavaHeaderCompileActionBuilder setDirectJars(NestedSet<Artifact> directJars) {
     checkNotNull(directJars, "directJars must not be null");
-    this.directJars.addAll(directJars);
+    this.directJars = directJars;
     return this;
   }
 
@@ -237,6 +236,13 @@ public class JavaHeaderCompileActionBuilder {
     checkNotNull(processorPath, "processorPath must not be null");
     checkNotNull(processorNames, "processorNames must not be null");
 
+    // Invariant: if strictJavaDeps is OFF, then directJars and
+    // dependencyArtifacts are ignored
+    if (strictJavaDeps == BuildConfiguration.StrictDepsMode.OFF) {
+      directJars = NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER);
+      compileTimeDependencyArtifacts.clear();
+    }
+
     SpawnAction.Builder builder = new SpawnAction.Builder();
 
     builder.addOutput(outputJar);
@@ -253,7 +259,7 @@ public class JavaHeaderCompileActionBuilder {
     builder.addInputs(processorPath);
     builder.addInputs(sourceJars);
     builder.addInputs(sourceFiles);
-    builder.addInputs(directJars);
+    builder.addTransitiveInputs(directJars);
     builder.addInputs(compileTimeDependencyArtifacts);
 
     builder.addTool(javacJar);
@@ -331,13 +337,7 @@ public class JavaHeaderCompileActionBuilder {
     }
 
     if (strictJavaDeps != BuildConfiguration.StrictDepsMode.OFF) {
-      result.add(
-          new CustomMultiArgv() {
-            @Override
-            public Iterable<String> argv() {
-              return JavaCompileAction.addJarsToTargets(classpathEntries, directJars);
-            }
-          });
+      result.add(new JavaCompileAction.JarsToTargetsArgv(classpathEntries, directJars));
 
       if (!compileTimeDependencyArtifacts.isEmpty()) {
         result.addExecPaths("--deps_artifacts", compileTimeDependencyArtifacts);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaLibraryHelper.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaLibraryHelper.java
index 4112128e65..bd4409ddc2 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaLibraryHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaLibraryHelper.java
@@ -174,7 +174,7 @@ public final class JavaLibraryHelper {
     if (isStrict()) {
       directJars = getNonRecursiveCompileTimeJarsFromDeps();
       if (directJars != null) {
-        attributes.addDirectCompileTimeClassPathEntries(directJars);
+        attributes.addCompileTimeClassPathEntries(directJars);
         attributes.addDirectJars(directJars);
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaTargetAttributes.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaTargetAttributes.java
index 3a28c203be..415cb12139 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaTargetAttributes.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaTargetAttributes.java
@@ -83,7 +83,7 @@ public class JavaTargetAttributes {
 
     private BuildConfiguration.StrictDepsMode strictJavaDeps =
         BuildConfiguration.StrictDepsMode.OFF;
-    private final List<Artifact> directJars = new ArrayList<>();
+    private final NestedSetBuilder<Artifact> directJars = NestedSetBuilder.naiveLinkOrder();
     private final List<Artifact> compileTimeDependencyArtifacts = new ArrayList<>();
     private String ruleKind;
     private Label targetLabel;
@@ -174,15 +174,6 @@ public class JavaTargetAttributes {
       return this;
     }
 
-    public Builder addDirectCompileTimeClassPathEntries(Iterable<Artifact> entries) {
-      Preconditions.checkArgument(!built);
-      // The other version is preferred as it is more memory-efficient.
-      for (Artifact classPathEntry : entries) {
-        compileTimeClassPath.add(classPathEntry);
-      }
-      return this;
-    }
-
     public Builder setRuleKind(String ruleKind) {
       Preconditions.checkArgument(!built);
       this.ruleKind = ruleKind;
@@ -228,23 +219,21 @@ public class JavaTargetAttributes {
     }
 
     /**
-     * In tandem with strictJavaDeps, directJars represents a subset of the
-     * compile-time, classpath jars that were provided by direct dependencies.
-     * When strictJavaDeps is OFF, there is no need to provide directJars, and
-     * no extra information is passed to javac. When strictJavaDeps is set to
-     * WARN or ERROR, the compiler command line will include extra flags to
-     * indicate the warning/error policy and to map the classpath jars to direct
-     * or transitive dependencies, using the information in directJars. The extra
-     * flags are formatted like this (same for --indirect_dependency):
+     * In tandem with strictJavaDeps, directJars represents a subset of the compile-time, classpath
+     * jars that were provided by direct dependencies. When strictJavaDeps is OFF, there is no need
+     * to provide directJars, and no extra information is passed to javac. When strictJavaDeps is
+     * set to WARN or ERROR, the compiler command line will include extra flags to indicate the
+     * warning/error policy and to map the classpath jars to direct or transitive dependencies,
+     * using the information in directJars. The extra flags are formatted like this (same for
+     * --indirect_dependency): <pre>
      * --direct_dependency
      * foo/bar/lib.jar
      * //java/com/google/foo:bar
-     *
-     * @param directJars
+     * </pre>
      */
-    public Builder addDirectJars(Iterable<Artifact> directJars) {
+    public Builder addDirectJars(NestedSet<Artifact> directJars) {
       Preconditions.checkArgument(!built);
-      Iterables.addAll(this.directJars, directJars);
+      this.directJars.addTransitive(directJars);
       return this;
     }
 
@@ -339,7 +328,7 @@ public class JavaTargetAttributes {
           messages,
           sourceJars,
           classPathResources,
-          directJars,
+          directJars.build(),
           compileTimeDependencyArtifacts,
           ruleKind,
           targetLabel,
@@ -391,7 +380,7 @@ public class JavaTargetAttributes {
 
   private final ImmutableList<Artifact> classPathResources;
 
-  private final ImmutableList<Artifact> directJars;
+  private final NestedSet<Artifact> directJars;
   private final ImmutableList<Artifact> compileTimeDependencyArtifacts;
   private final String ruleKind;
   private final Label targetLabel;
@@ -399,9 +388,7 @@ public class JavaTargetAttributes {
   private final NestedSet<Artifact> excludedArtifacts;
   private final BuildConfiguration.StrictDepsMode strictJavaDeps;
 
-  /**
-   * Constructor of JavaTargetAttributes.
-   */
+  /** Constructor of JavaTargetAttributes. */
   private JavaTargetAttributes(
       Set<Artifact> sourceFiles,
       Set<Artifact> compileTimeJarFiles,
@@ -415,7 +402,7 @@ public class JavaTargetAttributes {
       List<Artifact> messages,
       List<Artifact> sourceJars,
       List<Artifact> classPathResources,
-      List<Artifact> directJars,
+      NestedSet<Artifact> directJars,
       List<Artifact> compileTimeDependencyArtifacts,
       String ruleKind,
       Label targetLabel,
@@ -433,7 +420,7 @@ public class JavaTargetAttributes {
     this.messages = ImmutableList.copyOf(messages);
     this.sourceJars = ImmutableList.copyOf(sourceJars);
     this.classPathResources = ImmutableList.copyOf(classPathResources);
-    this.directJars = ImmutableList.copyOf(directJars);
+    this.directJars = directJars;
     this.compileTimeDependencyArtifacts = ImmutableList.copyOf(compileTimeDependencyArtifacts);
     this.ruleKind = ruleKind;
     this.targetLabel = targetLabel;
@@ -441,7 +428,7 @@ public class JavaTargetAttributes {
     this.strictJavaDeps = strictJavaDeps;
   }
 
-  public List<Artifact> getDirectJars() {
+  public NestedSet<Artifact> getDirectJars() {
     return directJars;
   }