Changes to Set Velocity custom fields

the request property first_name became required

the request property last_name became required

api tag Internal - Not for publishers added

api tag Internal removed

added the non-success response with the status 400

added the non-success response with the status 409

added the non-success response with the status 412

added the non-success response with the status 422

added the non-success response with the status 428

added the non-success response with the status 503