tomcat datasource native connection

Sometimes need use native db connection.
For example, to correct the following exception:

java.lang.ClassCastException: org.apache.tomcat.dbcp.dbcp.PoolingDataSource cannot be cast to oracle.jdbc.OracleConnection

  private String datasource = "java:comp/env/jdbc/mydb";

  private DataSource getDataSource() {
    InitialContext ctx;
    try {
      ctx = new InitialContext();
      BasicDataSource ds = (BasicDataSource) ctx.lookup(datasource);
      ds.setAccessToUnderlyingConnectionAllowed(true);
      return ds;
    } catch (NamingException e) {
      throw new RuntimeException(e);
    }
  }

  private Connection getNativeConnection(Connection connection) {
    return ((DelegatingConnection) connection).getInnermostDelegate();
  }

  public void doIt() {
    Connection connection = null;
    try {
      connection = getDataSource().getConnection();
      Connection nativeConnection = getNativeConnection(connection);
      doSomethingWithNativeConnection(nativeConnection);
    } catch (SQLException e) {
      throw new RuntimeException(e);
    } finally {
      if (connection != null) {
        try {
          connection.close();
        } catch (SQLException e) {
          e.printStackTrace();
        }
      }
    }

  }

  private void doSomethingWithNativeConnection(Connection connection) {
    System.out.println(connection.getClass());
    /*- for oracle will be print:
     class oracle.jdbc.driver.T4CConnection
     */
    // ...
  }

For example context.xml below:

<Resource name="jdbc/mydb" auth="Container" type="javax.sql.DataSource"
maxActive="10" maxIdle="10" maxWait="10000" username="user" password="password"
driverClassName="oracle.jdbc.OracleDriver" url="jdbc:oracle:thin:@localhost:1521:orasid"
validationQuery="select 1 from dual" />