conn = getConnection(env, conn);
if (conn == null) conn = getConnection(env);
  public Value mysql_list_dbs(Env env,                              @Optional Mysqli conn)    throws Throwable  {    conn = getConnection(env, conn);    try {      return conn.validateConnection().getCatalogs();    } catch (Throwable e) {      log.log(Level.FINE, e.toString(), e);            return BooleanValue.FALSE;    }  }