I've caught an issue on JdbcMessageStore#addMessageToGroup, when groupNotExist == false, but query for createdDate ends up with:
Caused by: org.springframework.dao.EmptyResultDataAccessException: Incorrect result size: expected 1, actual 0
Because the group exists in the another region.
So, I see several queries don't have a parameter placeholder REGION=?.
It causes many issues, if want to use the same groupKey in the separate regions
By the way MongoDbMessageSource looks correct.
Workaround to use different groupKeys always, independently of region.