code: public <T> T getPropertyValue(ElementDescriptor<T> descriptor)
  	{
  		PropStat propStat = mPropStatByProperty.get(descriptor);
  		if (propStat == null)
  		{
  			return null;
  		}
  
  		return propStat.getPropertyValue(descriptor);
  	}
docs: Get the value of a specific property.
  
  @param descriptor
  The {@link XmlElementDescriptor} of the property to return.
  @return The property value, may be <code>null</code> if the property was not present or didn't contain any value (because it had a non-
  {@link HttpStatus#OK} status).