Spring Security Principal claim name in JwtAuthenticationConverter is null but documented default

Describe the bug

At JwtAuthenticationConverter the principalClaimName is null, but the setter method is documented

Sets the principal claim name. Defaults to {@link JwtClaimNames#SUB}.

Expected fix Initialize by default the principalClaimName to sub, preferrably by using constant JwtClaimNames.SUB

Comment From: jzheaux

Hi, @djechelon, thanks for the report.

I believe this is because if the name is null it uses the JwtAuthenticationToken constructor that defaults to SUB.

That said, it would be nicer if this logic were simplified.

Can you submit a PR that sets the claim name to SUB and then also simplifies the logic to always call the constructor that takes the claim value?