Generalize fix to not emit a -gensrc.jar if the annotation processor …

…classpath is

non-empty but there are no annotation processors to run.

PiperOrigin-RevId: 206244327

src/main/java/com/google/devtools/build/lib/rules/java/JavaCompilationHelper.java

@@ -461,10 +461,7 @@ public Artifact createGensrcJar(Artifact outputJar) {
    */
   public boolean usesAnnotationProcessing() {
     JavaTargetAttributes attributes = getAttributes();
-    return getJavacOpts().contains("-processor")
-        // The target may have a processorpath even if no annotation processors are enabled,
-        // so check for processor names.
-        || !attributes.plugins().plugins().processorClasses().isEmpty();
+    return getJavacOpts().contains("-processor") || attributes.plugins().hasProcessors();
   }
 
   /**

src/main/java/com/google/devtools/build/lib/rules/java/JavaPluginInfoProvider.java

@@ -111,8 +111,18 @@ public static JavaPluginInfoProvider empty() {
 
   public abstract JavaPluginInfo apiGeneratingPlugins();
 
+  /** Returns true if the provider has no associated data. */
   public boolean isEmpty() {
     // apiGeneratingPlugins is a subset of plugins, so checking if plugins is empty is sufficient
     return plugins().isEmpty();
   }
+
+  /**
+   * Returns true if the provider has any associated annotation processors (regardless of whether it
+   * has a classpath or data).
+   */
+  public boolean hasProcessors() {
+    // apiGeneratingPlugins is a subset of plugins, so checking if plugins is empty is sufficient
+    return !plugins().processorClasses().isEmpty();
+  }
 }