Changes to Get requests via Relay

added the optional property edges/items/node/initiated_by_user_id to the response with the 200 status

added the optional property edges/items/node/source to the response with the 200 status

added the new CALLOUT enum value to the edges/items/node/custom_fields_responses/items/field_type response property for the response status 200

added the new MULTI_SELECT enum value to the edges/items/node/custom_fields_responses/items/field_type response property for the response status 200

response property edges/items/node/reviewer_stages list-of-types was widened by adding types string to media type application/json of response 200