Before this commit, specifying the charset to use with produces or
consumes @RequestMapping attributes resulted in default charset
loss. That was really annoying for JSON for example, where using
UTF-8 charset is mandatory in a lot of use cases.
This commit adds a defaultCharset property to
AbstractHttpMessageConverter in order to avoid losing the
default charset when specifying the charset with these
@RequestMapping attributes.
It changes slightly the default behavior (that's why we have waited
4.3), but it is much more error prone, and will match with most
user's expectations since the charset loss was accidental in most
use cases (users usually just want to limit the media type supported
by a specific handler method).
Issue: SPR-13631