ExtractList should handle v1.RawExtension correctly

Also fixes CustomColumnPrinter to pass decoder in, and ensures a test
case tests the combined path.

pkg/api/meta/help.go

@@ -72,12 +72,17 @@ func ExtractList(obj runtime.Object) ([]runtime.Object, error) {
 	for i := range list {
 		raw := items.Index(i)
 		switch item := raw.Interface().(type) {
+		case runtime.RawExtension:
+			switch {
+			case item.Object != nil:
+				list[i] = item.Object
+			case item.RawJSON != nil:
+				list[i] = &runtime.Unknown{RawJSON: item.RawJSON}
+			default:
+				list[i] = nil
+			}
 		case runtime.Object:
 			list[i] = item
-		case runtime.RawExtension:
-			list[i] = &runtime.Unknown{
-				RawJSON: item.RawJSON,
-			}
 		default:
 			var found bool
 			if list[i], found = raw.Addr().Interface().(runtime.Object); !found {