In the below example, I'm getting `[Manoj, Jeeva]` as output. But `[Hello Manoj, Hello Jeeva]` is the expected. Why serviceChnl is NOT giving output to aggregate?

```
 @Bean
  public IntegrationFlow sayHelloIntFlow() {
    return IntegrationFlows.from("serviceChnl")
                           .handle(new GenericHandler<String>() {
                             public Object handle(String payload, Map<String, Object> headers) {
                               return "Hello " + payload;
                             }
                           })
                           .get();
  }

@Bean
  public IntegrationFlow splitFlow() {
    return IntegrationFlows.from("splitChnl")
                           .split()
                           .channel("serviceChnl")
                           .aggregate()
                           .handle(new GenericHandler() {
                             public Object handle(Object payload, Map headers) {
                               System.out.println(payload);
                               return null;
                             }
                           })
                           .channel("nullChannel")
                           .get();
  }

@Test
  public void test() {
    String[] strArr = new String[] {"Manoj", "Jeeva"};
    Message msg = MessageBuilder.withPayload(strArr)
                                .build();
    splitChnl.send(msg);
  }

```