Repository: kubernetes/klog (go)

Issue:
Fix `InfoS` serializing Stringer subfields
/kind bug

**What steps did you take and what happened:**

When migrating `Infof` to `InfoS` there was a regression in serializing Stringer subfields.
```
klog.V(2).Infof("status for pod %v updated to %v", p.Name, status)
```
was correctly migrated to 
```
klog.V(2).InfoS("Pod status updated", "pod", klog.KObj(p), "status", status)
```
Log output before migration
```
I0601 19:25:53.698080   16895 kubelet_getters.go:173] status for pod nginx-pod-127.0.0.1 updated to {Running [{Initialized True 0001-01-01 00:00:00 +0000 UTC 2020-06-01 19:18:54 +0900 JST  } {Ready True 0001-01-01 00:00:00 +0000 UTC 2020-06-01 19:18:54 +0900 JST  } {ContainersReady True 0001-01-01 00:00:00 +0000 UTC 2020-06-01 19:18:54 +0900 JST  } {PodScheduled True 0001-01-01 00:00:00 +0000 UTC 2020-06-01 19:18:54 +0900 JST  }]    127.0.0.1 172.17.0.4 [{172.17.0.4}] 2020-06-01 19:18:54 +0900 JST [] [{nginx-container {nil &ContainerStateRunning{StartedAt:2020-06-01 18:27:34 +0900 JST,} nil} {nil nil nil} true 0 nginx:latest docker-pullable://nginx@sha256:6fff55753e3b34e36e24e37039ee9eae1fe38a6420d8ae16ef37c92d1eb26699 docker://c729caca14fd6b19fb1fdbf5fe436352abd31c488a134fd5e56ee9fe7dc98eaa 0xc0012c2069}] BestEffort []}
```
log output after migration
```
I0601 19:45:29.666416   27921 kubelet_getters.go:173] "Pod status updated" pod="default/nginx-pod-127.0.0.1" status=v1.PodStatus{Phase:"Running", Conditions:[]v1.PodCondition{v1.PodCondition{Type:"Initialized", Status:"True", LastProbeTime:v1.Time{Time:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}, LastTransitionTime:v1.Time{Time:time.Time{wall:0x0, ext:63726604110, loc:(*time.Location)(0x750f720)}}, Reason:"", Message:""}, v1.PodCondition{Type:"Ready", Status:"True", LastProbeTime:v1.Time{Time:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}, LastTransitionTime:v1.Time{Time:time.Time{wall:0x0, ext:63726604110, loc:(*time.Location)(0x750f720)}}, Reason:"", Message:""}, v1.PodCondition{Type:"ContainersReady", Status:"True", LastProbeTime:v1.Time{Time:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}, LastTransitionTime:v1.Time{Time:time.Time{wall:0x0, ext:63726604110, loc:(*time.Location)(0x750f720)}}, Reason:"", Message:""}, v1.PodCondition{Type:"PodScheduled", Status:"True", LastProbeTime:v1.Time{Time:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}}, LastTransitionTime:v1.Time{Time:time.Time{wall:0x0, ext:63726604110, loc:(*time.Location)(0x750f720)}}, Reason:"", Message:""}}, Message:"", Reason:"", NominatedNodeName:"", HostIP:"127.0.0.1", PodIP:"172.17.0.4", PodIPs:[]v1.PodIP{v1.PodIP{IP:"172.17.0.4"}}, StartTime:(*v1.Time)(0xc000d74220), InitContainerStatuses:[]v1.ContainerStatus(nil), ContainerStatuses:[]v1.ContainerStatus{v1.ContainerStatus{Name:"nginx-container", State:v1.ContainerState{Waiting:(*v1.ContainerStateWaiting)(nil), Running:(*v1.ContainerStateRunning)(0xc000d74200), Terminated:(*v1.ContainerStateTerminated)(nil)}, LastTerminationState:v1.ContainerState{Waiting:(*v1.ContainerStateWaiting)(nil), Running:(*v1.ContainerStateRunning)(nil), Terminated:(*v1.ContainerStateTerminated)(nil)}, Ready:true, RestartCount:0, Image:"nginx:latest", ImageID:"docker-pullable://nginx@sha256:6fff55753e3b34e36e24e37039ee9eae1fe38a6420d8ae16ef37c92d1eb26699", ContainerID:"docker://c729caca14fd6b19fb1fdbf5fe436352abd31c488a134fd5e56ee9fe7dc98eaa", Started:(*bool)(0xc000f7f1a9)}}, QOSClass:"BestEffort", EphemeralContainerStatuses:[]v1.ContainerStatus(nil)}
```

**What did you expect to happen:**
I would expect that type `time.Time` that implements stringer should be serialized using `.String()` instead of
`time.Time{wall:0x0, ext:63726604110, loc:(*time.Location)(0x750f720)}` 

**Anything else you would like to add:**
[Miscellaneous information that will assist in solving the issue.]


Pull request description:
fix imported bug InfoS time encode format 
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**What this PR does / why we need it**:
fix imported bug time encode format form kvlistFormat
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #156 

**Special notes for your reviewer**:

_Please confirm that if this PR changes any image versions, then that's the sole change this PR makes._

**Release note**:
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2. If no release note is required, just write "NONE".
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```release-note
NONE
```

Patch:
diff --git a/klog.go b/klog.go
index de49e85..ac3fbb0 100644
--- a/klog.go
+++ b/klog.go
@@ -800,10 +800,16 @@ func kvListFormat(b *bytes.Buffer, keysAndValues ...interface{}) {
 			v = missingValue
 		}
 		b.WriteByte(' ')
-		if _, ok := v.(fmt.Stringer); ok {
+
+		switch v.(type) {
+		case string:
 			b.WriteString(fmt.Sprintf("%s=%q", k, v))
-		} else {
-			b.WriteString(fmt.Sprintf("%s=%#v", k, v))
+		default:
+			if _, ok := v.(fmt.Stringer); ok {
+				b.WriteString(fmt.Sprintf("%s=%q", k, v))
+			} else {
+				b.WriteString(fmt.Sprintf("%s=%+v", k, v))
+			}
 		}
 	}
 }


Test patch:
diff --git a/klog_test.go b/klog_test.go
index 58b384e..40a0ca3 100644
--- a/klog_test.go
+++ b/klog_test.go
@@ -849,20 +849,21 @@ func TestKvListFormat(t *testing.T) {
 			keysValues: []interface{}{"pod", "kubedns", "spec", struct {
 				X int
 				Y string
-			}{X: 76, Y: "strval"}},
-			want: " pod=\"kubedns\" spec=struct { X int; Y string }{X:76, Y:\"strval\"}",
+				N time.Time
+			}{X: 76, Y: "strval", N: time.Date(2006, 1, 2, 15, 4, 5, .067890e9, time.UTC)}},
+			want: " pod=\"kubedns\" spec={X:76 Y:strval N:2006-01-02 15:04:05.06789 +0000 UTC}",
 		},
 		{
 			keysValues: []interface{}{"pod", "kubedns", "values", []int{8, 6, 7, 5, 3, 0, 9}},
-			want:       " pod=\"kubedns\" values=[]int{8, 6, 7, 5, 3, 0, 9}",
+			want:       " pod=\"kubedns\" values=[8 6 7 5 3 0 9]",
 		},
 		{
 			keysValues: []interface{}{"pod", "kubedns", "values", []string{"deployment", "svc", "configmap"}},
-			want:       " pod=\"kubedns\" values=[]string{\"deployment\", \"svc\", \"configmap\"}",
+			want:       " pod=\"kubedns\" values=[deployment svc configmap]",
 		},
 		{
 			keysValues: []interface{}{"pod", "kubedns", "maps", map[string]int{"three": 4}},
-			want:       " pod=\"kubedns\" maps=map[string]int{\"three\":4}",
+			want:       " pod=\"kubedns\" maps=map[three:4]",
 		},
 		{
 			keysValues: []interface{}{"pod", KRef("kube-system", "kubedns"), "status", "ready"},