gRPC migration update

Change-Id: Icdd1a824948fa994cd36bd121c962f5ecf74e3cf
diff --git a/vendor/github.com/uber/jaeger-client-go/tracer.go b/vendor/github.com/uber/jaeger-client-go/tracer.go
index 8a3fc97..9a627be 100644
--- a/vendor/github.com/uber/jaeger-client-go/tracer.go
+++ b/vendor/github.com/uber/jaeger-client-go/tracer.go
@@ -216,10 +216,10 @@
 		options.StartTime = t.timeNow()
 	}
 
-	// Predicate whether the given span context is a valid reference
-	// which may be used as parent / debug ID / baggage items source
-	isValidReference := func(ctx SpanContext) bool {
-		return ctx.IsValid() || ctx.isDebugIDContainerOnly() || len(ctx.baggage) != 0
+	// Predicate whether the given span context is an empty reference
+	// or may be used as parent / debug ID / baggage items source
+	isEmptyReference := func(ctx SpanContext) bool {
+		return !ctx.IsValid() && !ctx.isDebugIDContainerOnly() && len(ctx.baggage) == 0
 	}
 
 	var references []Reference
@@ -235,7 +235,7 @@
 				reflect.ValueOf(ref.ReferencedContext)))
 			continue
 		}
-		if !isValidReference(ctxRef) {
+		if isEmptyReference(ctxRef) {
 			continue
 		}
 
@@ -245,14 +245,17 @@
 			continue
 		}
 
-		references = append(references, Reference{Type: ref.Type, Context: ctxRef})
+		if ctxRef.IsValid() {
+			// we don't want empty context that contains only debug-id or baggage
+			references = append(references, Reference{Type: ref.Type, Context: ctxRef})
+		}
 
 		if !hasParent {
 			parent = ctxRef
 			hasParent = ref.Type == opentracing.ChildOfRef
 		}
 	}
-	if !hasParent && isValidReference(parent) {
+	if !hasParent && !isEmptyReference(parent) {
 		// If ChildOfRef wasn't found but a FollowFromRef exists, use the context from
 		// the FollowFromRef as the parent
 		hasParent = true
@@ -317,7 +320,7 @@
 	sp.references = references
 	sp.firstInProcess = rpcServer || sp.context.parentID == 0
 
-	if !sp.isSamplingFinalized() {
+	if !sp.context.isSamplingFinalized() {
 		decision := t.sampler.OnCreateSpan(sp)
 		sp.applySamplingDecision(decision, false)
 	}
@@ -410,7 +413,7 @@
 // calling client-side span, but obviously the server side span is
 // no longer a root span of the trace.
 func (t *Tracer) emitNewSpanMetrics(sp *Span, newTrace bool) {
-	if !sp.isSamplingFinalized() {
+	if !sp.context.isSamplingFinalized() {
 		t.metrics.SpansStartedDelayedSampling.Inc(1)
 		if newTrace {
 			t.metrics.TracesStartedDelayedSampling.Inc(1)
@@ -434,9 +437,11 @@
 }
 
 func (t *Tracer) reportSpan(sp *Span) {
-	if !sp.isSamplingFinalized() {
+	ctx := sp.SpanContext()
+
+	if !ctx.isSamplingFinalized() {
 		t.metrics.SpansFinishedDelayedSampling.Inc(1)
-	} else if sp.context.IsSampled() {
+	} else if ctx.IsSampled() {
 		t.metrics.SpansFinishedSampled.Inc(1)
 	} else {
 		t.metrics.SpansFinishedNotSampled.Inc(1)
@@ -445,7 +450,7 @@
 	// Note: if the reporter is processing Span asynchronously then it needs to Retain() the span,
 	// and then Release() it when no longer needed.
 	// Otherwise, the span may be reused for another trace and its data may be overwritten.
-	if sp.context.IsSampled() {
+	if ctx.IsSampled() {
 		t.reporter.Report(sp)
 	}