What Does This Do

Fixes an orphaned async continuation in Netty 4.1 HTTP/2 client flows.

For HTTP/1, the connect continuation captured in ConnectAdvice is later consumed by the request handler. In HTTP/2 prior-knowledge mode, the continuation is captured on the connection channel but requests are written on stream channels, so the continuation was never consumed or canceled.

This change marks channels that have an HTTP/2 connection codec as HTTP/2 connections and skips capturing the connect continuation for them. This avoids creating a continuation with no consumer. The request handler now also checks the parent channel for an existing connect continuation, covering stream-channel request paths where a parent-channel continuation is valid.

Issue spotted using an experimental continuation lifecycle tracker that gave:

continuation #35 captured-never-activated-or-canceled
    captured by: captureActiveSpan
    span: parent trace_id=9 span_id=8
    capture thread: reactor-http-nio-6
    activations=0, closed_scopes=0, cancels=0
    capture stack:
      at io.netty.channel.DefaultChannelPipeline.connect(DefaultChannelPipeline.java:978)
      at io.netty.channel.AbstractChannel.connect(AbstractChannel.java:253)
      at reactor.netty.transport.TransportConnector.lambda$doConnect$3(TransportConnector.java:149)
      at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98)

Motivation

Additional Notes

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Jira ticket: [PROJ-IDENT]