Currently JwtParser has mutator/configuration methods that modify the parser state (require* methods, setClock, signingKeyResolver, compressionCodecResolver, etc).

All of these methods should be in a JwtParserBuilder interface that has a build() method that returns a JwtParser instance.

This can be introduced before 1.0 and a Jwts.parserBuilder() method introduced and that should be documented as the primary/preferred mechanism moving forward. Jwts.parser() and all existing mutators in the JwtParser interface should be deprecated prior to 1.0 and then removed entirely for the 1.0 release.