SEBA-902 single-olt tests;
Pin protoc-gen-go to 1.3.2 to resolve compatibility issue;
Run go mod tidy / go mod vendor on importer;
Add Go Module support to demotest

Change-Id: Ifde824fc9a6317b0adc1e12bea54ee1f9b788906
diff --git a/vendor/google.golang.org/grpc/clientconn.go b/vendor/google.golang.org/grpc/clientconn.go
index f58740b..293d2f6 100644
--- a/vendor/google.golang.org/grpc/clientconn.go
+++ b/vendor/google.golang.org/grpc/clientconn.go
@@ -35,10 +35,10 @@
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/connectivity"
 	"google.golang.org/grpc/credentials"
-	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/internal/backoff"
 	"google.golang.org/grpc/internal/channelz"
 	"google.golang.org/grpc/internal/grpcsync"
+	"google.golang.org/grpc/internal/grpcutil"
 	"google.golang.org/grpc/internal/transport"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/resolver"
@@ -151,7 +151,7 @@
 	if channelz.IsOn() {
 		if cc.dopts.channelzParentID != 0 {
 			cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, cc.dopts.channelzParentID, target)
-			channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
+			channelz.AddTraceEvent(cc.channelzID, 0, &channelz.TraceEventDesc{
 				Desc:     "Channel Created",
 				Severity: channelz.CtINFO,
 				Parent: &channelz.TraceEventDesc{
@@ -161,10 +161,7 @@
 			})
 		} else {
 			cc.channelzID = channelz.RegisterChannel(&channelzChannel{cc}, 0, target)
-			channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
-				Desc:     "Channel Created",
-				Severity: channelz.CtINFO,
-			})
+			channelz.Info(cc.channelzID, "Channel Created")
 		}
 		cc.csMgr.channelzID = cc.channelzID
 	}
@@ -241,14 +238,14 @@
 	}
 
 	// Determine the resolver to use.
-	cc.parsedTarget = parseTarget(cc.target)
-	grpclog.Infof("parsed scheme: %q", cc.parsedTarget.Scheme)
+	cc.parsedTarget = grpcutil.ParseTarget(cc.target)
+	channelz.Infof(cc.channelzID, "parsed scheme: %q", cc.parsedTarget.Scheme)
 	resolverBuilder := cc.getResolver(cc.parsedTarget.Scheme)
 	if resolverBuilder == nil {
 		// If resolver builder is still nil, the parsed target's scheme is
 		// not registered. Fallback to default resolver and set Endpoint to
 		// the original target.
-		grpclog.Infof("scheme %q not registered, fallback to default scheme", cc.parsedTarget.Scheme)
+		channelz.Infof(cc.channelzID, "scheme %q not registered, fallback to default scheme", cc.parsedTarget.Scheme)
 		cc.parsedTarget = resolver.Target{
 			Scheme:   resolver.GetDefaultScheme(),
 			Endpoint: target,
@@ -416,12 +413,7 @@
 		return
 	}
 	csm.state = state
-	if channelz.IsOn() {
-		channelz.AddTraceEvent(csm.channelzID, &channelz.TraceEventDesc{
-			Desc:     fmt.Sprintf("Channel Connectivity change to %v", state),
-			Severity: channelz.CtINFO,
-		})
-	}
+	channelz.Infof(csm.channelzID, "Channel Connectivity change to %v", state)
 	if csm.notifyChan != nil {
 		// There are other goroutines waiting on this channel.
 		close(csm.notifyChan)
@@ -671,9 +663,9 @@
 		return
 	}
 
-	grpclog.Infof("ClientConn switching balancer to %q", name)
+	channelz.Infof(cc.channelzID, "ClientConn switching balancer to %q", name)
 	if cc.dopts.balancerBuilder != nil {
-		grpclog.Infoln("ignoring balancer switching: Balancer DialOption used instead")
+		channelz.Info(cc.channelzID, "ignoring balancer switching: Balancer DialOption used instead")
 		return
 	}
 	if cc.balancerWrapper != nil {
@@ -681,22 +673,12 @@
 	}
 
 	builder := balancer.Get(name)
-	if channelz.IsOn() {
-		if builder == nil {
-			channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
-				Desc:     fmt.Sprintf("Channel switches to new LB policy %q due to fallback from invalid balancer name", PickFirstBalancerName),
-				Severity: channelz.CtWarning,
-			})
-		} else {
-			channelz.AddTraceEvent(cc.channelzID, &channelz.TraceEventDesc{
-				Desc:     fmt.Sprintf("Channel switches to new LB policy %q", name),
-				Severity: channelz.CtINFO,
-			})
-		}
-	}
 	if builder == nil {
-		grpclog.Infof("failed to get balancer builder for: %v, using pick_first instead", name)
+		channelz.Warningf(cc.channelzID, "Channel switches to new LB policy %q due to fallback from invalid balancer name", PickFirstBalancerName)
+		channelz.Infof(cc.channelzID, "failed to get balancer builder for: %v, using pick_first instead", name)
 		builder = newPickfirstBuilder()
+	} else {
+		channelz.Infof(cc.channelzID, "Channel switches to new LB policy %q", name)
 	}
 
 	cc.curBalancerName = builder.Name()
@@ -720,6 +702,7 @@
 // Caller needs to make sure len(addrs) > 0.
 func (cc *ClientConn) newAddrConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (*addrConn, error) {
 	ac := &addrConn{
+		state:        connectivity.Idle,
 		cc:           cc,
 		addrs:        addrs,
 		scopts:       opts,
@@ -736,7 +719,7 @@
 	}
 	if channelz.IsOn() {
 		ac.channelzID = channelz.RegisterSubChannel(ac, cc.channelzID, "")
-		channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
+		channelz.AddTraceEvent(ac.channelzID, 0, &channelz.TraceEventDesc{
 			Desc:     "Subchannel Created",
 			Severity: channelz.CtINFO,
 			Parent: &channelz.TraceEventDesc{
@@ -834,7 +817,7 @@
 func (ac *addrConn) tryUpdateAddrs(addrs []resolver.Address) bool {
 	ac.mu.Lock()
 	defer ac.mu.Unlock()
-	grpclog.Infof("addrConn: tryUpdateAddrs curAddr: %v, addrs: %v", ac.curAddr, addrs)
+	channelz.Infof(ac.channelzID, "addrConn: tryUpdateAddrs curAddr: %v, addrs: %v", ac.curAddr, addrs)
 	if ac.state == connectivity.Shutdown ||
 		ac.state == connectivity.TransientFailure ||
 		ac.state == connectivity.Idle {
@@ -854,7 +837,7 @@
 			break
 		}
 	}
-	grpclog.Infof("addrConn: tryUpdateAddrs curAddrFound: %v", curAddrFound)
+	channelz.Infof(ac.channelzID, "addrConn: tryUpdateAddrs curAddrFound: %v", curAddrFound)
 	if curAddrFound {
 		ac.addrs = addrs
 	}
@@ -1025,7 +1008,7 @@
 				Severity: channelz.CtINFO,
 			}
 		}
-		channelz.AddTraceEvent(cc.channelzID, ted)
+		channelz.AddTraceEvent(cc.channelzID, 0, ted)
 		// TraceEvent needs to be called before RemoveEntry, as TraceEvent may add trace reference to
 		// the entity being deleted, and thus prevent it from being deleted right away.
 		channelz.RemoveEntry(cc.channelzID)
@@ -1068,15 +1051,8 @@
 	if ac.state == s {
 		return
 	}
-
-	updateMsg := fmt.Sprintf("Subchannel Connectivity change to %v", s)
 	ac.state = s
-	if channelz.IsOn() {
-		channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
-			Desc:     updateMsg,
-			Severity: channelz.CtINFO,
-		})
-	}
+	channelz.Infof(ac.channelzID, "Subchannel Connectivity change to %v", s)
 	ac.cc.handleSubConnStateChange(ac.acbw, s, lastErr)
 }
 
@@ -1213,12 +1189,7 @@
 		}
 		ac.mu.Unlock()
 
-		if channelz.IsOn() {
-			channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
-				Desc:     fmt.Sprintf("Subchannel picks a new address %q to connect", addr.Addr),
-				Severity: channelz.CtINFO,
-			})
-		}
+		channelz.Infof(ac.channelzID, "Subchannel picks a new address %q to connect", addr.Addr)
 
 		newTr, reconnect, err := ac.createTransport(addr, copts, connectDeadline)
 		if err == nil {
@@ -1300,7 +1271,7 @@
 	newTr, err := transport.NewClientTransport(connectCtx, ac.cc.ctx, target, copts, onPrefaceReceipt, onGoAway, onClose)
 	if err != nil {
 		// newTr is either nil, or closed.
-		grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v. Err :%v. Reconnecting...", addr, err)
+		channelz.Warningf(ac.channelzID, "grpc: addrConn.createTransport failed to connect to %v. Err: %v. Reconnecting...", addr, err)
 		return nil, nil, err
 	}
 
@@ -1308,7 +1279,7 @@
 	case <-time.After(time.Until(connectDeadline)):
 		// We didn't get the preface in time.
 		newTr.Close()
-		grpclog.Warningf("grpc: addrConn.createTransport failed to connect to %v: didn't receive server preface in time. Reconnecting...", addr)
+		channelz.Warningf(ac.channelzID, "grpc: addrConn.createTransport failed to connect to %v: didn't receive server preface in time. Reconnecting...", addr)
 		return nil, nil, errors.New("timed out waiting for server handshake")
 	case <-prefaceReceived:
 		// We got the preface - huzzah! things are good.
@@ -1355,7 +1326,7 @@
 		// The health package is not imported to set health check function.
 		//
 		// TODO: add a link to the health check doc in the error message.
-		grpclog.Error("Health check is requested but health check function is not set.")
+		channelz.Error(ac.channelzID, "Health check is requested but health check function is not set.")
 		return
 	}
 
@@ -1385,15 +1356,9 @@
 		err := ac.cc.dopts.healthCheckFunc(ctx, newStream, setConnectivityState, healthCheckConfig.ServiceName)
 		if err != nil {
 			if status.Code(err) == codes.Unimplemented {
-				if channelz.IsOn() {
-					channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
-						Desc:     "Subchannel health check is unimplemented at server side, thus health check is disabled",
-						Severity: channelz.CtError,
-					})
-				}
-				grpclog.Error("Subchannel health check is unimplemented at server side, thus health check is disabled")
+				channelz.Error(ac.channelzID, "Subchannel health check is unimplemented at server side, thus health check is disabled")
 			} else {
-				grpclog.Errorf("HealthCheckFunc exits with unexpected error %v", err)
+				channelz.Errorf(ac.channelzID, "HealthCheckFunc exits with unexpected error %v", err)
 			}
 		}
 	}()
@@ -1458,7 +1423,7 @@
 		ac.mu.Lock()
 	}
 	if channelz.IsOn() {
-		channelz.AddTraceEvent(ac.channelzID, &channelz.TraceEventDesc{
+		channelz.AddTraceEvent(ac.channelzID, 0, &channelz.TraceEventDesc{
 			Desc:     "Subchannel Deleted",
 			Severity: channelz.CtINFO,
 			Parent: &channelz.TraceEventDesc{