Given the Accept header:

Accept: application/json, */*

And the set of variants:

["application/xml","application/json"]

request.selectVariant(...) will choose application/xml. Assuming variant selection should follow the HTTP protocol behavior for the Accept header, this should not be the case:

Media ranges can be overridden by more specific media ranges or specific media types. If more than one media range applies to a given type, the most specific reference has precedence. HTTP spec, section 14.1