@FormatMethod
  private void reportError(Element e, String msg, Object... msgParams) {
    String formattedMessage = String.format(msg, msgParams);
    processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, formattedMessage, e);
  }
Issue a compilation error. This method does not throw an exception, since we want to continue
processing and perhaps report other errors.
value/src/main/java/com/google/auto/value/processor/AutoAnnotationProcessor.java