fix(pod/util): typos in getting pod validation options

Before, containers with the PostStart sleep lifecycle hook would cause
null pointer panics due to a typo in the field name being checked. This
commit fixes that.

The check also needs to be done on the oldPodSpec, rather than the
podSpec, so that existing workloads which use the zero value continue
functioning in the same way.

pkg/api/pod/util_test.go

@@ -4657,3 +4657,92 @@ func TestValidateInvalidLabelValueInNodeSelectorOption(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateAllowPodLifecycleSleepActionZeroValue(t *testing.T) {
+	testCases := []struct {
+		name                                        string
+		podSpec                                     *api.PodSpec
+		expectAllowPodLifecycleSleepActionZeroValue bool
+	}{
+		{
+			name:    "no lifecycle hooks",
+			podSpec: &api.PodSpec{},
+			expectAllowPodLifecycleSleepActionZeroValue: false,
+		},
+		{
+			name: "Prestop with non-zero second duration",
+			podSpec: &api.PodSpec{
+				Containers: []api.Container{
+					{
+						Lifecycle: &api.Lifecycle{
+							PreStop: &api.LifecycleHandler{
+								Sleep: &api.SleepAction{
+									Seconds: 1,
+								},
+							},
+						},
+					},
+				},
+			},
+			expectAllowPodLifecycleSleepActionZeroValue: false,
+		},
+		{
+			name: "PostStart with non-zero second duration",
+			podSpec: &api.PodSpec{
+				Containers: []api.Container{
+					{
+						Lifecycle: &api.Lifecycle{
+							PostStart: &api.LifecycleHandler{
+								Sleep: &api.SleepAction{
+									Seconds: 1,
+								},
+							},
+						},
+					},
+				},
+			},
+			expectAllowPodLifecycleSleepActionZeroValue: false,
+		},
+		{
+			name: "PreStop with zero seconds",
+			podSpec: &api.PodSpec{
+				Containers: []api.Container{
+					{
+						Lifecycle: &api.Lifecycle{
+							PreStop: &api.LifecycleHandler{
+								Sleep: &api.SleepAction{
+									Seconds: 0,
+								},
+							},
+						},
+					},
+				},
+			},
+			expectAllowPodLifecycleSleepActionZeroValue: true,
+		},
+		{
+			name: "PostStart with zero seconds",
+			podSpec: &api.PodSpec{
+				Containers: []api.Container{
+					{
+						Lifecycle: &api.Lifecycle{
+							PostStart: &api.LifecycleHandler{
+								Sleep: &api.SleepAction{
+									Seconds: 0,
+								},
+							},
+						},
+					},
+				},
+			},
+			expectAllowPodLifecycleSleepActionZeroValue: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			gotOptions := GetValidationOptionsFromPodSpecAndMeta(&api.PodSpec{}, tc.podSpec, nil, nil)
+			assert.Equal(t, tc.expectAllowPodLifecycleSleepActionZeroValue, gotOptions.AllowPodLifecycleSleepActionZeroValue, "AllowPodLifecycleSleepActionZeroValue")
+		})
+	}
+}