Facebook attributes not included in JSON API request body

Hi, I've added the facebook attributes first_name and last_name to my JSON API. But they're not being included in the request body. All the other custom attributes are set correctly. Do I have to do anything for it to work? Thanks.

I've added the facebook attributes first_name and last_name to my JSON API. But they're not being included in the request body. All the other custom attributes are  ...

Lee mas