To override thread pools/factories/timer of a protocol, one must do the following:

UDP udp = new UDP();
udp.init(); // Creates default pools
udp.setThreadPool(...); // Destroys default pool first

If I try to avoid the unnecessary thread creation/destruction by the following:

UDP udp = new UDP();
udp.setThreadPool(...);
udp.init();

... then my custom pools get overridden by the default implementations.

Instead, Protocol.init() should check to see if implementations already exist before instantiating the default implementations.