Update go dependencies for kubernetes 1.16.0

vendor/k8s.io/apimachinery/pkg/util/net/http.go

@@ -101,6 +101,9 @@ func SetOldTransportDefaults(t *http.Transport) *http.Transport {
 	if t.TLSHandshakeTimeout == 0 {
 		t.TLSHandshakeTimeout = defaultTransport.TLSHandshakeTimeout
 	}
+	if t.IdleConnTimeout == 0 {
+		t.IdleConnTimeout = defaultTransport.IdleConnTimeout
+	}
 	return t
 }
 
@@ -111,7 +114,7 @@ func SetTransportDefaults(t *http.Transport) *http.Transport {
 	// Allow clients to disable http2 if needed.
 	if s := os.Getenv("DISABLE_HTTP2"); len(s) > 0 {
 		klog.Infof("HTTP2 has been explicitly disabled")
-	} else {
+	} else if allowsHTTP2(t) {
 		if err := http2.ConfigureTransport(t); err != nil {
 			klog.Warningf("Transport failed http2 configuration: %v", err)
 		}
@@ -119,6 +122,21 @@ func SetTransportDefaults(t *http.Transport) *http.Transport {
 	return t
 }
 
+func allowsHTTP2(t *http.Transport) bool {
+	if t.TLSClientConfig == nil || len(t.TLSClientConfig.NextProtos) == 0 {
+		// the transport expressed no NextProto preference, allow
+		return true
+	}
+	for _, p := range t.TLSClientConfig.NextProtos {
+		if p == http2.NextProtoTLS {
+			// the transport explicitly allowed http/2
+			return true
+		}
+	}
+	// the transport explicitly set NextProtos and excluded http/2
+	return false
+}
+
 type RoundTripperWrapper interface {
 	http.RoundTripper
 	WrappedRoundTripper() http.RoundTripper