This patch removes the default user name and password for Oracle, H2, and Derby.
This will always work in Derby as Derby doesn't check user names and passwords by default.
For Oracle and H2 the problem is backward compatibility: if user name and password was not configured in previous installations, the old default values (sa for H2, crx for Oracle) were used. For Oracle, a user name and password is required in any case. I think this is a problem, but the best way to solve it is (in my view) to document this change in the release notes.
If nobody objects, I will commit this change in a few days.