Data mapper doesn't map anything when incoming data shape is a collection

When trying to do a test of OData where I read a collection of entities from the service, send it all to data mapper and try to update an entity, the correct behavior should be that only the last entity is updated because the Data Mapper maps every entity one after each other, and then when it's done with the mapping, outputs only the last entity.

But right now the data mapper outputs blank values:

instead of "Description":"Flat Basic", "keyPredicate":"5" it outputs "Description":"", "keyPredicate":""

so the integration ends with error because of the blank keyPredicate (http://pastebin.test.redhat.com/803156)

other then that, the integration doesn't seem to throw any error while executing the data mapper step: http://pastebin.test.redhat.com/803159

the doesn't seem to be any errors in the server pod log.