code: @Override
      protected void sendClientMessage(Throwable throwable) {
          if (throwable instanceof ScheduledTaskResult.ExecutionExceptionDecorator) {
              super.sendClientMessage(throwable.getCause());
          } else {
              super.sendClientMessage(throwable);
          }
      }
docs: Exceptions may be wrapped in ExecutionExceptionDecorator, the wrapped ExecutionException should be sent to
  the client.
  @param throwable