@Override
    public <T> T getJsonProperty(final String key, final Class<T> clazz, final T defaultValue) {
        return null;
    }
set file name.
@param fileName fileName
shenyu-sync-data-center/shenyu-sync-data-polaris/src/test/java/org/apache/shenyu/sync/data/polaris/handler/PolarisMockConfigFile.java