public String get(String key, String defaultValue) {
        addToDefaults(key, defaultValue);
        String value = get(key);
        if (value == null) {
            return defaultValue;
        } else {
            return value;
        }
    }
Returns the String value for the given key. If the key does not exist it will return the
given default value.
inlong-sort/sort-common/src/main/java/org/apache/inlong/sort/util/ParameterTool.java