Set Java version to 7
Especially in order to avoid test related code in the production environment. (see #12869 (moved) about util.Time).
I currently cannot point to an exploit or similar, but having something (non-static) standing in between java.lang.System.millisec and the application does not feel right.
So, a Mocking Framework might be a way to solve this. The framework should be compatible with the Guidelines.
(I could look into it. So, I have a reason to study the Guidelines thoroughly.)