Using an instance lock to protect static shared data in EmbedPooledConnection

EmbedPooledConnection has the unsafe synchronization as follow.

private static int idCounter = 0;

private synchronized int nextId()

{ return idCounter++; }

idCounter is a static shared data, and it is not proper to use a instance lock to protect it, especially when two instance of the class are created.

it would be more safer to write this instead:

private static synchronized int nextId()
{ return idCounter++; }