Get the endpoint that timed out in TimeoutAwareAggregationStrategy

I am having a hard time finding out which endpoint timeout when using the
TimeoutAwareAggregationStrategy; the timeout method callback is called. My
requirement is to send a message to a status queue when a timeout occurs
with the endpoint which timed out.

The timeout method in TimeoutAwareAggregationStrategy takes in Exchange
oldExchange, int index, int total, long timeout.

I imagine that the index can be used to get the endpoint that timed out but
I am not able to find out how to get it. Any help is appreciated. Thanks.