Disable auto-configuration of HiddenHttpMethodFilter by default

[vpavic]

WebMvcAutoConfiguration currently configures a lot of components that are specific to use of Spring MVC with a templating engine to produce server-side generated text/html content. An example of this is HiddenHttpMethodFilter, which is enabled by default. Such components present an unnecessary overhead when Spring MVC is solely used to produce e.g. application/json based APIs.

This has caught my attention after we discovered that the aforementioned HiddenHttpMethodFilter has been taking up to 80% of processing time on certain endpoints. While it was simple enough to disable the filter using spring.mvc.hiddenmethod.filter.enabled property, you have to do it in each project and I believe configuration could be made more lightweight there. In the case of this particular filter, a case could be made that it's not really needed even in all projects that use a templating engine.

[philwebb]

I'm not sure we've got a good signal that we won't need the HiddenHttpMethodFilter. Perhaps we could make it conditional on a ViewResolver bean. It feels a bit risky.

@vpavic I'm curious why HiddenHttpMethodFilter was taking so much time, it doesn't seem to do all that much. Did you ever discover the cause?

[vpavic]

Before opening this issue I also explored options around ViewResolver being the condition but wasn't able to come up with anything since defaultViewResolver (which is InternalResourceViewResolver) will always be there.

The endpoints that were affected by this were accepting MultipartFile request parameter - we didn't look that deep in since disabling the filter basically fixed the problem and improved performance significantly but I assume this was related to size of the request as HiddenHttpMethodFilter does ServletRequest#getParameter. Here's an example of how it looked in New Relic:

Anyway, after taking a closer look at WebMvcAutoConfiguration I realized that significant part of it was not needed where you're using Spring MVC to simply serve API and not server-side generated HTML. Having in mind that nowadays a setup like this is quite common I'd like to see Spring Boot provide a way to have more suitable (i.e. reduced) set of MVC components registered.