docs: @SuppressWarnings("nls")
  	private void checkNotNull(Object sourceClass, Object eventSetName, Object alistenerType, Object listenerMethodName)
  	{
  		if (sourceClass == null)
  		{
  			throw new NullPointerException(Messages.getString("beans.0C"));
  		}
  		if (eventSetName == null)
  		{
  			throw new NullPointerException(Messages.getString("beans.53"));
  		}
  		if (alistenerType == null)
  		{
  			throw new NullPointerException(Messages.getString("beans.54"));
  		}
  		if (listenerMethodName == null)
  		{
  			throw new NullPointerException(Messages.getString("beans.52"));
  		}
  	}