@Override
    public String getProperty(final String key, final String defaultValue) {
        return properties.getProperty(key, defaultValue);
    }
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