code: public void removeListener(Rdp4jListener listener) {
          if (listener == null) {
              throw new NullPointerException(NULL_ARGUMENT_ERROR);
          }
          scheduledRunnable.removeListener(listener);
      }
docs: Removes the given <code>listener</code> from this instance.
  The <code>listener</code> will be removed after any ongoing
  poll-cycles has finished. If there's no ongoing poll-cycles,
  then the given <code>listener</code> will be removed just before
  next poll-cycle is started.
  
  @param listener implementation of any of the sub-interfaces of {@link Rdp4jListener}
  -interface.
  @throws NullPointerException if the given argument is null.e