Spring MimeTypeUtils no longer cache MediaType.MULTIPART_FORM_DATA_VALUE

For example "multipart/form-data; boundary=----WebKitFormBoundarymKzwdDkWNDNzQFP0", this mimeType with random characters, wastes LRU cache space, resulting in severe performance degradation.

This pull-request fixed it

Comment From: bclozel

Thanks for the PR, but boundaries can appear in other MIME types. This has been fixed in #24767.