@Override
    public void printStackTrace() {
        super.printStackTrace();
        if (nestedThrowable != null) {
            nestedThrowable.printStackTrace();
        }
    }
Exception used for representing that the requested operation is forbidden for the user in 
the MUCRoom. There are many reasons why a forbidden error could occur such as: a banned user
tries to join a room where he/she is an outcast. A 403 error code is returned to the user that 
requested the invalid operation.

@author Gaston Dombiak
xmppserver/src/main/java/org/jivesoftware/openfire/muc/ForbiddenException.java