Error registered the JDBC driver [oracle.jdbc.driver.OracleDriver] but failed to unregister

I am making a JavaWeb system using jsp that is in this topic: Doubt in query database, error in query , and in a query with the database, I came across a driver error that is Right below. I use the netbeans IDE with server glassfish and the Oracle database.

Error:

  

Warning : The web application [/ road] registered the JDBC driver [oracle.jdbc.driver.OracleDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

Connection class:

public class Conexao {

private Connection conexao;

public Conexao() {
    try {
        Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
        String url = "jdbc:oracle:thin:@127.0.0.1:1521:XE";
        conexao = DriverManager.getConnection(url,"rafilds","1234");
  } catch (Exception e) {
        e.printStackTrace();
    }
}

public Connection getConexao() {
    return conexao;
}
}