Unintended alternating endpoints in flow - spring-integration

Question

I have a flow that is similar to
IntegrationFlows.from(
Http.inboundGateway("/events")
.requestMapping(requestMappingSpec -> {
requestMappingSpec.methods(HttpMethod.POST);
requestMappingSpec.consumes(MediaType.APPLICATION_JSON_VALUE);
requestMappingSpec.produces(MediaType.APPLICATION_JSON_VALUE);
})
.requestPayloadType(PushEvent.class)
.errorChannel(ERROR_CHANNEL))
.channel(ReleaseFlow.REQUEST_CHANNEL)
.enrichHeaders(h -> h
.header(HttpHeaders.STATUS_CODE, HttpStatus.ACCEPTED))
.get();
When submitting multiple requests, a request will be processed by the flow attached to the REQUEST_CHANNEL and the following request will be processed by just the enrichedHeaders. My understanding is that the endpoints in this example should be processed serially ...
A request arrives at the /events endpoint
The request is processed by the flow listening to REQUEST_CHANNEL
The response from the previous flow will then have its headers enriched
The flow ends and the response is returned to the remote requestor
I appreciate your help in understanding why request n is processed by the channel (and not enrichHeaders()), request n + 1 is being processed by enrichHeaders() (and not the flow listening to the REQUEST_CHANNEL), request n + 2 processed by the channel (and not enrichHeaders()), ...
UPDATE 1
I am new to Spring Integration, but thought it was appropriate to collect events from a GitHub server and then create a release using an external service. The integration service would be responsible for determining the appropriate workflow based upon the data associated to the commit. The endpoint in question would receive a push event and forward it to the flow attached to the subscribable request channel (REQUEST_CHANNEL). This second flow will make a number of outbound requests to collect the appropriate release template and construct and start the pipeline.
UPDATE 2
I have not developed the second flow completely at this point, but here is a first version that simply performs a transformation based upon data associated with the commit.
return f -> f
.route(branchRouter(), mapping -> mapping
.subFlowMapping(true, t -> t
.transform(pushEventToEventTransformer()))
.subFlowMapping(false, n -> n
.transform(skip -> "")));
When the code has been submitted to a "monitored" branch the actions described in the first update will be performed. I am attempting to build the flows incrementally given my limited knowledge of the framework.

Answer 1

Subscribable channels are point-to-point by default, which means if there are two subscribers, messages will be distributed in round-robin fashion.
If you have another flow " ... attached to the REQUEST_CHANNEL " then you have two subscribers - that flow and the header-enricher.
Perhaps if you can describe what you are trying to do we can help.
With the header enricher after the channel, all that happens is the headers are enriched and the inbound message is returned to the gateway.
Perhaps you want this... ?
IntegrationFlows.from(
Http.inboundGateway("/events")
.requestMapping(requestMappingSpec -> {
requestMappingSpec.methods(HttpMethod.POST);
requestMappingSpec.consumes(MediaType.APPLICATION_JSON_VALUE);
requestMappingSpec.produces(MediaType.APPLICATION_JSON_VALUE);
})
.requestPayloadType(PushEvent.class)
.errorChannel(ERROR_CHANNEL))
.enrichHeaders(h -> h
.header(HttpHeaders.STATUS_CODE, HttpStatus.ACCEPTED))
.channel(ReleaseFlow.REQUEST_CHANNEL)
.get();
Which means all messages with the enriched headers will be sent to the channel.
EDIT
If you want the message to go to both places, you need to use a publish-subscribe channel.