This asynchronous flow has always been specified in RFC8555 [https://datatracker.ietf.org/doc/html/rfc8555#:~:text=A%20request%20to%20finalize%20an%20order%20will%20result%20in%20error,to%20the%20%22certificate%22%20field%20of%20the%20order.%20%20Download%20the%0A%20%20%20%20%20%20certificate.](https://datatracker.ietf.org/doc/html/rfc8555#:%7E:text=A%20request%20to%20finalize%20an%20order%20will%20result%20in%20error,to%20the%20%22certificate%22%20field%20of%20the%20order.%20%20Download%20the%0A%20%20%20%20%20%20certificate.)