Support changing the group owner via REST

A new owner group for a group can now be set by PUT on
'/groups/<group>/owner'.

The WebUI was adapted to use this new REST endpoint.

Change-Id: I1c921d65855f9ade91aa9b5db91a6001570d1c6d
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-server/src/main/java/com/google/gerrit/server/group/GetOwner.java

@@ -0,0 +1,46 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// 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 com.google.gerrit.server.group;
+
+import com.google.gerrit.common.errors.NoSuchGroupException;
+import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
+import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.reviewdb.client.AccountGroup;
+import com.google.gerrit.server.account.GroupControl;
+import com.google.inject.Inject;
+
+public class GetOwner implements RestReadView<GroupResource> {
+
+  private final GroupControl.Factory controlFactory;
+
+  @Inject
+  GetOwner(GroupControl.Factory controlFactory) {
+    this.controlFactory = controlFactory;
+  }
+
+  @Override
+  public Object apply(GroupResource resource) throws ResourceNotFoundException {
+    AccountGroup group = resource.toAccountGroup();
+    if (group == null) {
+      throw new ResourceNotFoundException();
+    }
+    try {
+      GroupControl c = controlFactory.validateFor(group.getOwnerGroupUUID());
+      return new GroupInfo(c.getGroup());
+    } catch (NoSuchGroupException e) {
+      throw new ResourceNotFoundException();
+    }
+  }
+}