UnstructuredList should return 'items' set to the children

The set of items is not mutable (can't add or remove items) but the list
now is. Needs to be improved to make mutability is clear.

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured/unstructured.go

@@ -73,11 +73,24 @@ func (obj *Unstructured) UnstructuredContent() map[string]interface{} {
 	}
 	return obj.Object
 }
+
+// UnstructuredContent returns a map contain an overlay of the Items field onto
+// the Object field. Items always overwrites overlay. Changing "items" in the
+// returned object will affect items in the underlying Items field, but changing
+// the "items" slice itself will have no effect.
+// TODO: expose SetUnstructuredContent on runtime.Unstructured that allows
+// items to be changed.
 func (obj *UnstructuredList) UnstructuredContent() map[string]interface{} {
-	if obj.Object == nil {
-		obj.Object = make(map[string]interface{})
+	out := obj.Object
+	if out == nil {
+		out = make(map[string]interface{})
 	}
-	return obj.Object
+	items := make([]interface{}, len(obj.Items))
+	for i, item := range obj.Items {
+		items[i] = item.Object
+	}
+	out["items"] = items
+	return out
 }
 
 // MarshalJSON ensures that the unstructured object produces proper

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured/unstructured_test.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package unstructured
+
+import "testing"
+
+func TestUnstructuredList(t *testing.T) {
+	list := &UnstructuredList{
+		Object: map[string]interface{}{"kind": "List", "apiVersion": "v1"},
+		Items: []*Unstructured{
+			{Object: map[string]interface{}{"kind": "Pod", "apiVersion": "v1", "metadata": map[string]interface{}{"name": "test"}}},
+		},
+	}
+	content := list.UnstructuredContent()
+	items := content["items"].([]interface{})
+	if len(items) != 1 {
+		t.Fatalf("unexpected items: %#v", items)
+	}
+	if getNestedField(items[0].(map[string]interface{}), "metadata", "name") != "test" {
+		t.Fatalf("unexpected fields: %#v", items[0])
+	}
+}