Elytron token-realm doesn't support unsigned tokens

Verification of JWT tokens with empty signature part fails in Elytron.

The Elytron token-realm can be configured to not verify JWT token signature.

/subsystem=elytron/token-realm=JwtRealm:add(jwt={})

The JWT specification describes tokens without signature in RFC 7519 Section 6.

When user is comming with such a token the validation in Elytron fails.

Sample token:

eyJhbGciOiJub25lIiwidHlwIjoiSldUIn0.eyJpc3MiOiJpc3N1ZXIud2lsZGZseS5vcmciLCJzdWIiOiJlbHl0cm9uQHdpbGRmbHkub3JnIiwiZXhwIjoyMDUxMjIyMzk5LCJhdWQiOiJlbHl0cm9uLXRlc3QifQ.

Header:
{
  "alg": "none",
  "typ": "JWT"
}

Payload:
{
  "iss": "issuer.wildfly.org",
  "sub": "elytron@wildfly.org",
  "exp": 2051222399,
  "aud": "elytron-test"
}

The problem is probably in this piece of code in JwtValidator class:

        String[] parts = jwt.split("\\.");

        if (parts.length < 3) {
            throw log.tokenRealmJwtInvalidFormat();
        }

Even if the token correctly contains 2 dots, the split returns array of lenght 2 (because the last part is empty). Additional negative-integer argument to the split() method could help here:

jwt.split("\\.", -1);