create connectionSource with MySQL driver v6

DbHelper.java

    /**
     * The data source instance that need to be public so we can close it in on-app-exit hook
     */
    private DataSource initDataSource(HikariConfig config) {
        return new HikariDataSource(config);
    }

    private ConnectionSource initConnectionSource(DataSource ds) throws SQLException {
        return new DataSourceConnectionSource(ds, new MySql6DbType());
    }