Yeah to avoid any changes, you can just return the oldExchange if its not null.
And no you cannot tell the aggregator to skip in certain situations, for that as said, just return the old exchange.
However the aggregation have some options to configure what should happen for
- late messages
- invalid messages
See the options table on its documentation
I only found an attribute named ignoreInvalidCorelationKeys which seems to be enough to solve my problem. Thanks.