Spring Provide public getter or part converter registration in FormHttpMessageConverter for partConverters

Spring Boot has a reflection hack so that it can register additional part converters (see https://github.com/spring-projects/spring-boot/issues/23485). It would be good to at least provide a public API for doing that. Maybe go a bit further in 6.0?

Comment From: rstoyanchev

A getter should be straight forward. Is 5.3 sufficient or does it help be in 5.2 as well?

Comment From: dsyer

I think 5.3 is all we need.