Support for an async determination of status and headers with a WebMvc HandlerFunction #25828
Description
HandlerFunction returns ServerResponse which supports providing a Publisher or CompletableFuture for the body but there is no way to determine the response status and headers asynchronously like there is in WebFlux where the return value is Mono<ServerResponse.
A specific case in point is a GraphQL over HTTP endpoint for which headers of the response may need to be customized after async query execution, but the same argument applies for any case where the response status and headers may only be decided after some async operation.