@Override
  public final synchronized void init(ProcessingEnvironment processingEnv) {
    super.init(processingEnv);
    this.elementUtils = processingEnv.getElementUtils();
    this.messager = processingEnv.getMessager();
    this.steps = ImmutableList.copyOf(steps());
  }
Elements that were explicitly deferred in some {@link Step} by being returned from {@link
Step#process}.
common/src/main/java/com/google/auto/common/BasicAnnotationProcessor.java