if ev := fx.WaitOrFail(t, "xds full"); !ev.Reason.Has(model.EndpointUpdate) {
			t.Fatalf("xds push reason does not contain %v: %v", model.EndpointUpdate, ev)
		}
		// headless service update must trigger nds push, so we trigger a full push.
		if ev := fx.WaitOrFail(t, "xds full"); !ev.Reason.Has(model.HeadlessEndpointUpdate) {
			t.Fatalf("xds push reason does not contain %v: %v", model.HeadlessEndpointUpdate, ev)
		}

var (
	// ErrNotSupported indicates that a feature is not supported.
	//
	// It is returned by ResponseController methods to indicate that
	// the handler does not support the method, and by the Push method
	// of Pusher implementations to indicate that HTTP/2 Push support
	// is not available.
	ErrNotSupported = &ProtocolError{"feature not supported"}

	// Deprecated: ErrUnexpectedTrailer is no longer returned by