This commit introduces a `useRegisteredExtensionsOnly` property that
indicates whether classes that use the `MediaTypeFactory` for supplying
default media types can do so.
- In classes that were introduced in Spring 5.0, the
`useRegisteredExtensionsOnly` property takes the place of the
`useJaf` property that was removed in 0aaa652
- In classes that existed before Spring 5.0, the
`useRegisteredExtensionsOnly` property is added in addition to the
deprecated `useJaf`, the latter delegating to the former, but with
flipped behavior.
Issue: SPR-14908
a287e67992