@Override
    public void setCallbackExecutor(final ExecutorService callbackExecutor) {
        this.callbackExecutor = callbackExecutor;
    }
@Test
    public void testSetCallbackExecutor() {
        ExecutorService customized = Executors.newCachedThreadPool();
        remotingClient.setCallbackExecutor(customized);
        assertThat(remotingClient.getCallbackExecutor()).isEqualTo(customized);
    }