Prior to Spring Framework 5.1.3, MimeTypeUtils.parseMimeTypes() and
MediaType.parseMediaTypes() ignored empty entries, but 5.1.3 introduced
a regression in that an empty entry -- for example, due to a trailing
comma in the list of media types in an HTTP Accept header -- would result
in a "406 Not Acceptable" response status.
This commit fixes this by filtering out empty entries before parsing
them into MimeType and MediaType instances. Empty entries are therefore
effectively ignored.
Fixes gh-23241