message: Prefer `connection.flush` over `connection.stream.flush`
diff: @@ -470,7 +470,7 @@ impl Connection {
  Ok(())
  }
  - async fn flush(&mut self) -> Result<(), io::Error> {
  + pub(crate) async fn flush(&mut self) -> Result<(), io::Error> {
  self.stream.flush().await
  }
  }
  @@ -636,7 +636,7 @@ impl ConnectionHandler {
  }
  }
  - self.connection.stream.flush().await?;
  + self.connection.flush().await?;
  Ok(())
  }
  @@ -666,7 +666,7 @@ impl ConnectionHandler {
  self.connection
  .write_op(ClientOp::Unsubscribe { sid, max: None })
  .await?;
  - self.connection.stream.flush().await?;
  + self.connection.flush().await?;
  // if channel was open and we sent the messsage, increase the
  // `delivered` counter.
  } else {
  