private String option(String key) {
        if (!configured)
            throw new IllegalStateException("Callback handler not configured");
        return moduleOptions.get(Objects.requireNonNull(key));
    }
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