com.mysql.jdbc.Driver和org.gjt.mm.mysql.Driver的疑问

通过查看源码，发现原来org.git.mm.mysql.Driver是com.mysql.jdbc.Driver的子类：

public class Driver extends com.mysql.jdbc.Driver {
    /**
     * Creates a new instance of Driver
     * 
     * @throws SQLException
     *             if a database error occurs.
     */
    public Driver() throws SQLException {
        super();
    }
}