Duplicate Issue Keys can be created

Although rare, it has been reported by at least one customer that duplicate Issues Keys may be created.

By looking at the code it seems that this may be possible under the following circumstances:

• A request to create an issue is received and gets the relevant project from the Project Manager.
• The Project Manager refreshes its cache of Projects.
• A second request to create an issue is received and gets the new Project object.
• Now, the two separate instances of Project can try to use the same key.

This is all dependant on concurrent operations happening in a particular sequence, and would be more likely to happen on a JIRA server that was under high load.