spring-web: 5.2.0
The media type APPLICATION_PROBLEM_JSON_UTF8 has incorrect value application/problem;charset=UTF-8 instead of application/problem+json;charset=UTF-8 missing the +json part.

APPLICATION_PROBLEM_JSON_UTF8 = new MediaType("application", "problem", StandardCharsets.UTF_8);

This causes regression like:

org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class fully.qualified.name.of.our.Exception] with preset Content-Type 'application/problem;charset=UTF-8'