Changes to Get billing agreements

the response property agreements/items/billing_group_id became nullable for the status 200 (media type: application/json; charset=utf-8)

the response property agreements/items/billing_group_id became nullable for the status 200 (media type: application/json)

the response property agreements/items/expires_on became nullable for the status 200 (media type: application/json; charset=utf-8)

the response property agreements/items/expires_on became nullable for the status 200 (media type: application/json)

added the optional property agreements/items/current_period_end to the response with the 200 status (media type: application/json; charset=utf-8)

added the optional property agreements/items/current_period_end to the response with the 200 status (media type: application/json)

added the optional property agreements/items/current_period_start to the response with the 200 status (media type: application/json; charset=utf-8)

added the optional property agreements/items/current_period_start to the response with the 200 status (media type: application/json)

endpoint added