[REQ] In vertx-web template the response send is always json, need a mechanism to override the behaviour without changing the handler definition

The api handler mustache https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/JavaVertXWebServer/apiHandler.mustache, has a code

 .onSuccess(apiResponse -> {
                routingContext.response().setStatusCode(apiResponse.getStatusCode());
                if (apiResponse.hasData()) {
                    routingContext.json(apiResponse.getData());
                } else {
                    routingContext.response().end();
                }
            })

Thus the response is sent always as json to send let's say binary, user has to modify the generated handler code.

Let's modify the ApiResponse mustache https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/JavaVertXWebServer/supportFiles/ApiResponse.mustache as to include a function

    public void sendResponse(RoutingContext routingContext){
        if (this.hasData()) {
            routingContext.json(this.getData());
        } else {
            routingContext.response().end();
        }
    }

and use this function in the api handler mustache as

.onSuccess(apiResponse -> {
                routingContext.response().setStatusCode(apiResponse.getStatusCode());
                apiResponse.sendResponse(routingContext);
            })

This way user can simply override the function within ApiResponse as

                ApiResponse<String> apiResponse = new ApiResponse<String>(OK.code(),binaryString){
                    @Override
                    public void sendResponse(RoutingContext routingContext) {
                        routingContext.response().send(this.getData());
                    }
                };

I have done this and can raise PR if community feels can be used . Please suggest

Read modules/openapi-generator/src/main/resources/JavaVertXWebServer/apiHandler.mustache and its supportFiles/ApiResponse.mustache counterpart to trace how successful responses are sent. Verify that the generated Vert.x response path can be customized without editing the handler definition, and confirm that existing JSON and empty responses still behave as before.