RawExtension was not properly marshalled

MarshalJSON can't use a pointer to a struct for RawExtension:

http://stackoverflow.com/questions/21390979/custom-marshaljson-never-gets-called-in-go

pkg/runtime/extension.go

@@ -26,6 +26,8 @@ func (re *RawExtension) UnmarshalJSON(in []byte) error {
 	return nil
 }
 
-func (re *RawExtension) MarshalJSON() ([]byte, error) {
+// Marshal may get called on pointers or values, so implement MarshalJSON on value.
+// http://stackoverflow.com/questions/21390979/custom-marshaljson-never-gets-called-in-go
+func (re RawExtension) MarshalJSON() ([]byte, error) {
 	return re.RawJSON, nil
 }

pkg/runtime/extension_test.go

@@ -0,0 +1,39 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 runtime_test
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+)
+
+func TestEmbeddedRawExtensionMarshal(t *testing.T) {
+	type test struct {
+		Ext runtime.RawExtension
+	}
+
+	extension := test{Ext: runtime.RawExtension{RawJSON: []byte(`{"foo":"bar"}`)}}
+	data, err := json.Marshal(extension)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(data) != `{"Ext":{"foo":"bar"}}` {
+		t.Errorf("unexpected data: %s", string(data))
+	}
+}