Still there in 4.1.x.
I did replace the default listener (via SPI Integrator strategy) for the auto flush event with a custom listener which does make a copy of the HashSet as sugested as solution.

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira