private String generateKid(JsonValue jwkSet, String algorithm) { final JwsAlgorithm jwsAlgorithm = JwsAlgorithm.valueOf(algorithm); if (JwsAlgorithmType.RSA.equals(jwsAlgorithm.getAlgorithmType())) { JsonValue jwks = jwkSet.get(OAuth2Constants.JWTTokenParams.KEYS); if (!jwks.isNull() && !jwks.asList().isEmpty()) { return jwks.get(0).get(OAuth2Constants.JWTTokenParams.KEY_ID).asString(); } } return null; }