private int allowableClockSkewMs() {
        String allowableClockSkewMsValue = option(ALLOWABLE_CLOCK_SKEW_MILLIS_OPTION);
        int allowableClockSkewMs = 0;
        try {
            allowableClockSkewMs = Utils.isBlank(allowableClockSkewMsValue) ? 0 : Integer.parseInt(allowableClockSkewMsValue.trim());
        } catch (NumberFormatException e) {
            throw new OAuthBearerConfigException(e.getMessage(), e);
        }
        if (allowableClockSkewMs < 0) {
            throw new OAuthBearerConfigException(
                    String.format("Allowable clock skew millis must not be negative: %s", allowableClockSkewMsValue));
        }
        return allowableClockSkewMs;
    }
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