Changes to Update customer billing app data

the external_invoicing request property type changed from no type to object

the stripe request property type changed from no type to object

the response property external_invoicing became nullable for the status 200

the response property stripe became nullable for the status 200

the external_invoicing response's property type changed from no type to object for status 200

the stripe response's property type changed from no type to object for status 200

the request property external_invoicing became nullable

the request property stripe became nullable