Merge pull request kubernetes#93785 from SataQiu/fix-comment-20200807

Fix incorrect comment in runtime ObjectKind interface

Author: k8s-ci-robot

staging/src/k8s.io/apimachinery/pkg/runtime/schema/interfaces.go

@@ -23,8 +23,8 @@ type ObjectKind interface {
 	// SetGroupVersionKind sets or clears the intended serialized kind of an object. Passing kind nil
 	// should clear the current setting.
 	SetGroupVersionKind(kind GroupVersionKind)
-	// GroupVersionKind returns the stored group, version, and kind of an object, or nil if the object does
-	// not expose or provide these fields.
+	// GroupVersionKind returns the stored group, version, and kind of an object, or an empty struct
+	// if the object does not expose or provide these fields.
 	GroupVersionKind() GroupVersionKind
 }