private String confirmNotReservedClaimName(String claimName) throws OAuthBearerConfigException {
        if (RESERVED_CLAIMS.contains(claimName))
            throw new OAuthBearerConfigException(String.format("Cannot explicitly set the '%s' claim", claimName));
        return claimName;
    }
Add and validate all the configured extensions.
 Token keys, apart from passing regex validation, must not be equal to the reserved key {@link OAuthBearerClientInitialResponse#AUTH_KEY}
clients/src/main/java/org/apache/kafka/common/security/oauthbearer/internals/unsecured/OAuthBearerUnsecuredLoginCallbackHandler.java