public static String getString(String key, String defaultValue) {
        return get().getOrDefault(key, defaultValue);
    }
Gets value mapped to key, returning defaultValue if unmapped.

@param  key          to be found
@param  defaultValue returned if key is unmapped
@return              value associated with key
inlong-sort-standalone/sort-standalone-common/src/main/java/org/apache/inlong/sort/standalone/config/holder/CommonPropertiesHolder.java