docs: @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
      if (!roundEnv.processingOver()) {
        for (TypeElement te : annotations) {
          for (Element elt : roundEnv.getElementsAnnotatedWith(te)) {
            if (!elt.toString().startsWith("org.apache.heron")) {
              env.getMessager().printMessage(
                  Kind.WARNING,
                  String.format("%s extends from a class annotated with %s", elt, te),
                  elt);
            }
          }
        }
      }
      return true;
    }