As developer I would log some information about incoming webhook event, for example I would log everything happens on processors for debug purpose or gather statistic information like how many request processed worked with success, requests by event type and so on.

To avoid delay the response to Bitbucket, all listeners must be processed in async way. Each listener must process events from same request in an ordered way.

For example if we have an entry point when a WebhookProcessor implementation met incoming request and other entry point when the processor start processing it than the listener must first call "onStart" and only when it returns than process "onProcess".

Payload could (in some way) be attached as invisible action to next triggered running build.