RKAttributeMapping lose custom value transformer when RKObjectMapping is inverted

In RKObjectMapping
On invertMapping:withPredicate:

Each mapping.attributeMappings is recreated with source/destination keyPaths inverted but its propertyValueClass and valueTransformer are not copied from original attributeMapping

Solution:
Implemented and used a new copyPropertiesFromMapping: method for RKAttributeMapping in the same way it already was for RKObjectMapping
If not the transformer is never used.
Mmm, you mean that because the class is set before the inversion, it's probably related to the wrong side (ie the destination that inverted will be the source).
Actually I'm setting the Attribute Mapping with the knowledge that it's going to be inverted.

My req. is to POST a NSData object as NSNumber but I can't figure out how to do it without setting a custom transformer to the attribute mapping.

Should probably be defined a transformer for each mapping direction (source and destination)?