[Micronaut server] Add HttpResponse to controller methods

[pbthorste]

Description

Currently, methods generated by the micronaut server generator return objects such as;

public Mono<List<String>> .....

openapi-generator version

latest, 5.4.0

Suggest a fix/enhancement

It would be very useful if the micronaut server generator did something similar to the spring boot generator - return objects wrapped with HttpResponse. This gives alot more control.

So this file https://github.com/OpenAPITools/openapi-generator/blob/edfb3e123f0d3ad48992e158da957e87c3b8c3fe/modules/openapi-generator/src/main/resources/java-micronaut/server/controller.mustache

would be changed so that it returns:

public Mono<HttpResponse<List<String>>> .....

@andriy-dmytruk

[pbthorste]

thanks @andriy-dmytruk for adding this feature