The connectedToControl field was introduced to the API to allow callers to identify nodes that the Tailscale control server thinks are (or were recently) connected. connectedToControl should be used instead of lastSeen for determining whether a node is connected to the control plane, because lastSeen is only updated after nodes are no longer connected.

This fixes unexpected/buggy behavior of the endpoint, so it is being included in the deprecated v1 client as a hot fix.