I agree with the change of behaviour of close() so that its permanently closed.
However we relied on the current behaviour as a way of restarting the Connection Pool after changing its properties without a full JVM restart. (e.g. change the Database URL). I agree this is a hack and there is no guarantee it will continue to work.
But I think you might agree, is a useful feature to have. Looking at the source code, I spotted a restart() method which is currently private and not used, which just calls close().
Will it make sense to expose this method and have an overloaded method close(boolean permanent) which controls if its a permanent close or not.
If you agree, I am happy to submit a patch.