https://issues.apache.org/jira/browse/AMQ-6391

[pdudits]

Test case for multiple connections participating in one phase commit, causing leak in ConnectionStateTracker.

Keep all the connections participating in an transaction in a static multimap similar to the one in TransactionContext.

Even though Garry says that static fields may cause issues in OSGi, I am offering this as a solution. This static map has same lifecycle, classloading and source bundle as the one already present in TransactionContext, therefore I assume it cannot really make things worse.