If change MySQL JDBC driver from 5.1.38 to 6.0.2 I get the following exception
5.1.38
6.0.2
java.sql.SQLNonTransientConnectionException: CLIENT_PLUG
This sounds like a regression. Was there a particular reason to switch to 6.0.2? If not, I'd revert back to 5.1.38 and give 6.x a shot after three months to let folks at MySQL to stabilize the driver.