private String option(String key) {
        if (!configured)
            throw new IllegalStateException("Callback handler not configured");
        return moduleOptions.get(Objects.requireNonNull(key));
    }
Return true if this instance has been configured, otherwise false

@return true if this instance has been configured, otherwise false
clients/src/main/java/org/apache/kafka/common/security/oauthbearer/internals/unsecured/OAuthBearerUnsecuredValidatorCallbackHandler.java