[SNMP4J] missing usm.addUsmUserListener(usmMIB);

[Clement_Pellerin at ibi.com]

The AgentConfigManager should call usm.addUsmUserListener(usmMIB); just like the BaseAgent used to do.
Without this listener, you must populate the USM before it is passed to the usmMIB. This is fragile timing.
It is simpler to populate the USM after AgentConfigManager.initialize() is called rather than intercept a lower level method.
When you do that, the USM works, but the remote USM administration is broken because the MIB is not reflecting the USM config.