Consulted by an HTTP adapter for every inbound WebSocket upgrade request.
After M70a, the upgrade router is called through the kernel middleware
pipeline (via UPGRADE_INTENT), not before it. Returning null
means "this is not a WebSocket route" and the adapter falls through to
normal HTTP handling, so registering a router never changes the behavior
of non-WebSocket traffic.
Consulted by an HTTP adapter for every inbound WebSocket upgrade request.
After M70a, the upgrade router is called through the kernel middleware pipeline (via
UPGRADE_INTENT), not before it. Returningnullmeans "this is not a WebSocket route" and the adapter falls through to normal HTTP handling, so registering a router never changes the behavior of non-WebSocket traffic.