public List<PacketInterceptor> getUserInterceptors(String username) {
        List<PacketInterceptor> userInterceptors = usersInterceptors.get(username);
        if (userInterceptors == null) {
            return Collections.emptyList();
        }
        else {
            return Collections.unmodifiableList(userInterceptors);
        }
    }
Returns an unmodifable list of packet interceptors that are related to the
specified username.

@param username the name of the user.
@return an unmodifiable list of packet interceptors that are related to
     the specified username.
xmppserver/src/main/java/org/jivesoftware/openfire/interceptor/InterceptorManager.java