Now my use case is that I want to transfer 500 messages between these routes, and I use .throttle(500). But I also want to control that when the next batch of 500 messages should be routed. I want to route the next 500 messages only when the queue a2 becomes empty.
For example, messages are getting routed from queue a1 to a2. Say 500 messages have been routed successfully, now I want to suspend (or open circuit) of my route so that it won't transfer messages any further until the queue a2 becomes empty (there is a consumer which is pulling messages from queue a2)