I've had clients bitten by this twice in the past month, so it's worth filing now. The scenario is using JIRA and Crowd. They start with an internal directory and create users in all lowercase, e.g. jsmith. Life is good then they decide to use AD with Crowd. They create a new Crowd directory and it has the same users with some in a different case e.g. JSmith

Now when the user logs into JIRA they don't see issues that were assigned to them or reported by them or their own dashboards (very annoying that). The solution is to enable "force lowercase" in the Crowd Application for JIRA, restart JIRA and reindex JIRA.

Since JIRA expects lowercase users in many different places in its source, why not enable "force lowercase" by default. Or at least clearly document the consequences of leaving it disabled.