'Spring Integration - Aggregator - payload must not be null

I have a service activator and an aggregator like below. Some services do their jobs and gives the output to serviceActivatorInputChannel and then serviceActivatorInputChannel runs method of service and gives the output to aggregatorInputChannel.

<int:service-activator input-channel="serviceActivatorInputChannel"
                       output-channel="aggregatorInputChannel"
                       ref="service"
                       method="method"
                       requires-reply="true">
</int:service-activator> 

<int:aggregator input-channel="aggregatorInputChannel"
                ref="aggregatorService"
                method="aggregate"
                release-strategy="strategy"
                release-strategy-method="canRelease"
                correlation-strategy="correlationStrategy"
                correlation-strategy-method="getCorrelationKey"
                send-partial-result-on-expiry="false">
</int:aggregator>

Here is my getCorrelationKey method:

@Override
    public Object getCorrelationKey(Message<?> message)
    {
        logger.info("GetCorrelationKey received");
        if (message.getHeaders().containsKey("correlationId"))
            return message.getHeaders().get("correlationId");
        else
            return message.getHeaders().get(MessageHeaders.ID);
    }

As you see, there is only one point to give message to aggregator. The process is working like I want. The data is being processed properly but at the end of the process, I took below error. I don't know how and why aggregator is being called. Why am I getting that error?

java.lang.IllegalArgumentException: payload must not be null
    at org.springframework.util.Assert.notNull(Assert.java:201) ~[spring-core-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.support.MessageBuilder.<init>(MessageBuilder.java:68) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.support.MessageBuilder.withPayload(MessageBuilder.java:113) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.support.DefaultMessageBuilderFactory.withPayload(DefaultMessageBuilderFactory.java:71) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.support.DefaultMessageBuilderFactory.withPayload(DefaultMessageBuilderFactory.java:30) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.aggregator.AbstractAggregatingMessageGroupProcessor.processMessageGroup(AbstractAggregatingMessageGroupProcessor.java:103) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.aggregator.AbstractCorrelatingMessageHandler.completeGroup(AbstractCorrelatingMessageHandler.java:827) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.aggregator.AbstractCorrelatingMessageHandler.processMessageForGroup(AbstractCorrelatingMessageHandler.java:498) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.aggregator.AbstractCorrelatingMessageHandler.handleMessageInternal(AbstractCorrelatingMessageHandler.java:471) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.BroadcastingDispatcher.invokeHandler(BroadcastingDispatcher.java:224) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.BroadcastingDispatcher.dispatch(BroadcastingDispatcher.java:180) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:106) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:403) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:444) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:318) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:266) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:229) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:170) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:133) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
springspring-integration


Solution 1:[1]

See that stack trace carefully:

at org.springframework.integration.support.DefaultMessageBuilderFactory.withPayload(DefaultMessageBuilderFactory.java:30) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
at org.springframework.integration.aggregator.AbstractAggregatingMessageGroupProcessor.processMessageGroup(AbstractAggregatingMessageGroupProcessor.java:103) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]
at org.springframework.integration.aggregator.AbstractCorrelatingMessageHandler.completeGroup(AbstractCorrelatingMessageHandler.java:827) ~[spring-integration-core-5.2.11.RELEASE.jar:5.2.11.RELEASE]

That null payload comes from the Object payload = aggregatePayloads(group, headers);. The aggregatePayloads() implementation in your case delegates to that aggregatorService.aggregate() method. And exactly this one returns null for us.

So, please, revise your custom aggregation function to not return null.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Artem Bilan

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