@Override
    public Serializable getDefaultValue() {
        return defaultValue;
    }
Constructor of client option.

@param <T>          type of the value, usually either String or Number(e.g.
                    int, long etc.)
@param key          non-null key, better use snake_case instead of camelCase
                    for consistency
@param defaultValue non-null default value
@param description  non-null description of this option
@param sensitive    whether the option is sensitive or not
clickhouse-client/src/main/java/com/clickhouse/client/config/ClickHouseClientOption.java