Provide string constants for media types to use in annotations

[darioseidl]

It would be nice to have string constants of common media types to use in annotations, for example, for Spring's @RequestMapping or Swagger's @ApiResponse.

Spring has a very limited set of constants in org.springframework.http.MediaType, where each media is available as MediaType object and as string constant (with suffix _VALUE), e.g. MediaType.APPLICATION_JSON is the MediaType object and MediaType.APPLICATION_JSON_VALUE is the string constant application/json. That's very convenient, but they only provide a handful of media types.

Guava's com.google.common.net.MediaType provides the most complete set of media types that I know of, but sadly cannot be used as compile-time string constants in annotations. There's a StackOverflow Q/A about this too, in which Guava is recommended, but this limitation is pointed out too.

Would you consider adding such constants? I can imaging writing and maintaining such a list by hand wouldn't be fun, but maybe the code could be generated from the existing MediaType constants.

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A tiny side note: I saw this comment in the code,

  // TODO(gak): make these public?
  private static final String APPLICATION_TYPE = "application";
  private static final String AUDIO_TYPE = "audio";
  private static final String IMAGE_TYPE = "image";
  private static final String TEXT_TYPE = "text";
  private static final String VIDEO_TYPE = "video";

  private static final String WILDCARD = "*";

and yea, I think, it would be useful (and I don't see any harm?) if those constants would be public.