code: private <T> void addLimit(ElementDescriptor<T> descriptor, T limit)
  	{
  		if (mLimit == null)
  		{
  			mLimit = new HashMap<ElementDescriptor<?>, Object>(6);
  		}
  		mLimit.put(descriptor, limit);
  	}
docs: Add a limit to the request.
  
  @param descriptor
  The {@link ElementDescriptor} of the limit element.
  @param limit
  The limit value.