Merge "Update hooks plugin"
diff --git a/Documentation/dev-contributing.txt b/Documentation/dev-contributing.txt
index cc0fe60..bc9f782 100644
--- a/Documentation/dev-contributing.txt
+++ b/Documentation/dev-contributing.txt
@@ -368,6 +368,36 @@
 that they are vetted long enough before they go into a release and we can be sure
 that the update doesn't introduce a regression.
 
+[[deprecating-features]]
+=== Deprecating features
+
+Gerrit should be as stable as possible and we aim to add only features that last.
+However, sometimes we are required to deprecate and remove features to be able
+to move forward with the project and keep the code-base clean. The following process
+should serve as a guideline on how to deprecate functionality in Gerrit. Its purpose
+is that we have a structured process for deprecation that users, administrators and
+developers can agree and rely on.
+
+General process:
+* Make sure that the feature (e.g. a field on the API) is not needed anymore or blocks
+  further development or improvement. If in doubt, consult the mailing list.
+* If you can provide a schema migration that moves users to a comparable feature, do
+  so and stop here.
+* Mark the feature as deprecated in the documentation and release notes.
+* If possible, mark the feature deprecated in any user-visible interface. For example,
+  if you are deprecating a Git push option, add a message to the Git response if
+  the user provided the option informing them about deprecation.
+* Annotate the code with `@Deprecated` and `@RemoveAfter(x.xx)` if applicable.
+  Alternatively, use `// DEPRECATED, remove after x.xx` (where x.xx is the version
+  number that has to be branched off before removing the feature)
+* Gate the feature behind a config that is off by default (forcing admins to turn
+  the deprecated feature on explicitly).
+* After the next release was branched off, remove any code that backed the feature.
+
+You can optionally consult the mailing list to ask if there are users of the feature you
+wish to deprecate. If there are no major users, you can remove the feature without
+following this process and without the grace period of one release.
+
 GERRIT
 ------
 Part of link:index.html[Gerrit Code Review]
diff --git a/Documentation/dev-release.txt b/Documentation/dev-release.txt
index 2afac94..0abd8a1 100644
--- a/Documentation/dev-release.txt
+++ b/Documentation/dev-release.txt
@@ -365,6 +365,17 @@
 must reference the new version. Upload a change to bazlets repository with
 api version upgrade.
 
+[[clean-up-on-master]]
+=== Clean up on master
+
+Once you are done with the release, check if there are any code changes in the
+master branch that were gated on the next release. Mostly, these are
+feature-deprecations that we were holding off on to have a stable release where
+the feature is still contained, but marked as deprecated.
+
+See link:dev-contributing.html#deprecating-features[Deprecating features] for
+details.
+
 GERRIT
 ------
 Part of link:index.html[Gerrit Code Review]
diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
index 3587bf8..0f786a6 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/ChangeInfo.java
@@ -32,7 +32,6 @@
 import com.google.gwtjsonrpc.client.impl.ser.JavaSqlTimestamp_JsonSerializer;
 import java.sql.Timestamp;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -448,9 +447,8 @@
 
     public static void sortRevisionInfoByNumber(JsArray<RevisionInfo> list) {
       final int editParent = findEditParent(list);
-      Collections.sort(
-          Natives.asList(list),
-          comparing(r -> !r.isEdit() ? 2 * (r._number() - 1) + 1 : 2 * editParent));
+      Natives.asList(list)
+          .sort(comparing(r -> !r.isEdit() ? 2 * (r._number() - 1) + 1 : 2 * editParent));
     }
 
     public static int findEditParent(JsArray<RevisionInfo> list) {
diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
index 345a260..fc3dbf1 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/info/FileInfo.java
@@ -19,7 +19,6 @@
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
-import java.util.Collections;
 import java.util.Comparator;
 
 public class FileInfo extends JavaScriptObject {
@@ -55,8 +54,7 @@
   public final native void _row(int r) /*-{ this._row = r }-*/;
 
   public static void sortFileInfoByPath(JsArray<FileInfo> list) {
-    Collections.sort(
-        Natives.asList(list), Comparator.comparing(FileInfo::path, FilenameComparator.INSTANCE));
+    Natives.asList(list).sort(Comparator.comparing(FileInfo::path, FilenameComparator.INSTANCE));
   }
 
   public static String getFileName(String path) {
diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
index 4b17068..41306ff 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
@@ -14,11 +14,12 @@
 
 package com.google.gerrit.client.rpc;
 
+import static java.util.stream.Collectors.toCollection;
+
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.user.client.rpc.AsyncCallback;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
@@ -57,10 +58,7 @@
   }
 
   public final List<String> sortedKeys() {
-    Set<String> keys = keySet();
-    List<String> sorted = new ArrayList<>(keys);
-    Collections.sort(sorted);
-    return sorted;
+    return keySet().stream().sorted().collect(toCollection(ArrayList::new));
   }
 
   public final native JsArray<T> values() /*-{
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyGpgKeysScreen.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyGpgKeysScreen.java
index bbd94f2..1a0090a 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyGpgKeysScreen.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyGpgKeysScreen.java
@@ -42,7 +42,6 @@
 import com.google.gwtexpui.clippy.client.CopyableLabel;
 import com.google.gwtexpui.globalkey.client.NpTextArea;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 public class MyGpgKeysScreen extends SettingsScreen {
@@ -119,7 +118,7 @@
                     List<GpgKeyInfo> list = Natives.asList(result.values());
                     // TODO(dborowitz): Sort on something more meaningful, like
                     // created date?
-                    Collections.sort(list, comparing(GpgKeyInfo::id));
+                    list.sort(comparing(GpgKeyInfo::id));
                     keys.clear();
                     keyText.setText("");
                     errorPanel.setVisible(false);
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyIdentitiesScreen.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyIdentitiesScreen.java
index 5c6d40f..730d98e 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyIdentitiesScreen.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyIdentitiesScreen.java
@@ -14,6 +14,8 @@
 
 package com.google.gerrit.client.account;
 
+import static java.util.Comparator.naturalOrder;
+
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.VoidResult;
 import com.google.gerrit.client.rpc.GerritCallback;
@@ -29,7 +31,6 @@
 import com.google.gwt.user.client.ui.Button;
 import com.google.gwt.user.client.ui.CheckBox;
 import com.google.gwt.user.client.ui.FlexTable.FlexCellFormatter;
-import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 
@@ -169,7 +170,7 @@
 
     void display(JsArray<ExternalIdInfo> results) {
       List<ExternalIdInfo> idList = Natives.asList(results);
-      Collections.sort(idList);
+      idList.sort(naturalOrder());
 
       while (1 < table.getRowCount()) {
         table.removeRow(table.getRowCount() - 1);
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/AccessSectionEditor.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/AccessSectionEditor.java
index 1b946cd..7bd8b82 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/AccessSectionEditor.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/AccessSectionEditor.java
@@ -14,6 +14,8 @@
 
 package com.google.gerrit.client.admin;
 
+import static java.util.stream.Collectors.toCollection;
+
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.common.data.AccessSection;
 import com.google.gerrit.common.data.LabelType;
@@ -45,7 +47,6 @@
 import com.google.gwt.user.client.ui.HTMLPanel;
 import com.google.gwt.user.client.ui.ValueListBox;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 public class AccessSectionEditor extends Composite
@@ -205,9 +206,8 @@
   }
 
   private void sortPermissions(AccessSection accessSection) {
-    List<Permission> permissionList = new ArrayList<>(accessSection.getPermissions());
-    Collections.sort(permissionList);
-    accessSection.setPermissions(permissionList);
+    accessSection.setPermissions(
+        accessSection.getPermissions().stream().sorted().collect(toCollection(ArrayList::new)));
   }
 
   void setEditing(boolean editing) {
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/GroupTable.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/GroupTable.java
index c09f936..be0db41 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/GroupTable.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/GroupTable.java
@@ -34,7 +34,6 @@
 import com.google.gwt.user.client.ui.FlexTable.FlexCellFormatter;
 import com.google.gwt.user.client.ui.HTMLTable.Cell;
 import com.google.gwt.user.client.ui.Image;
-import java.util.Collections;
 import java.util.List;
 
 public class GroupTable extends NavigationTable<GroupInfo> {
@@ -106,7 +105,7 @@
       table.removeRow(table.getRowCount() - 1);
     }
 
-    Collections.sort(list, comparing(GroupInfo::name));
+    list.sort(comparing(GroupInfo::name));
     for (GroupInfo group : list.subList(fromIndex, toIndex)) {
       final int row = table.getRowCount();
       table.insertRow(row);
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Labels.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Labels.java
index 1f4820f..801a927 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Labels.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Labels.java
@@ -14,6 +14,10 @@
 
 package com.google.gerrit.client.change;
 
+import static java.util.stream.Collectors.collectingAndThen;
+import static java.util.stream.Collectors.toCollection;
+import static java.util.stream.Collectors.toList;
+
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.changes.ChangeApi;
 import com.google.gerrit.client.changes.Util;
@@ -135,9 +139,12 @@
   }
 
   void set(ChangeInfo info) {
-    List<String> names = new ArrayList<>(info.labels());
+    List<String> names =
+        info.labels()
+            .stream()
+            .sorted()
+            .collect(collectingAndThen(toList(), Collections::unmodifiableList));
     Set<Integer> removable = info.removableReviewerIds();
-    Collections.sort(names);
 
     resize(names.size(), 2);
 
@@ -197,8 +204,7 @@
   }
 
   private static List<Integer> sort(Set<Integer> keySet, int a, int b) {
-    List<Integer> r = new ArrayList<>(keySet);
-    Collections.sort(r);
+    List<Integer> r = keySet.stream().sorted().collect(toCollection(ArrayList::new));
     if (keySet.contains(a)) {
       r.remove(Integer.valueOf(a));
       r.add(0, a);
@@ -238,31 +244,32 @@
       Set<Integer> removable,
       String label,
       Map<Integer, VotableInfo> votable) {
-    List<AccountInfo> users = new ArrayList<>(in);
-    Collections.sort(
-        users,
-        new Comparator<AccountInfo>() {
-          @Override
-          public int compare(AccountInfo a, AccountInfo b) {
-            String as = name(a);
-            String bs = name(b);
-            if (as.isEmpty()) {
-              return 1;
-            } else if (bs.isEmpty()) {
-              return -1;
-            }
-            return as.compareTo(bs);
-          }
+    List<AccountInfo> users =
+        in.stream()
+            .sorted(
+                new Comparator<AccountInfo>() {
+                  @Override
+                  public int compare(AccountInfo a, AccountInfo b) {
+                    String as = name(a);
+                    String bs = name(b);
+                    if (as.isEmpty()) {
+                      return 1;
+                    } else if (bs.isEmpty()) {
+                      return -1;
+                    }
+                    return as.compareTo(bs);
+                  }
 
-          private String name(AccountInfo a) {
-            if (a.name() != null) {
-              return a.name();
-            } else if (a.email() != null) {
-              return a.email();
-            }
-            return "";
-          }
-        });
+                  private String name(AccountInfo a) {
+                    if (a.name() != null) {
+                      return a.name();
+                    } else if (a.email() != null) {
+                      return a.email();
+                    }
+                    return "";
+                  }
+                })
+            .collect(collectingAndThen(toList(), Collections::unmodifiableList));
 
     SafeHtmlBuilder html = new SafeHtmlBuilder();
     Iterator<? extends AccountInfo> itr = users.iterator();
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java
index 0bbd614..8a1a2d5 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java
@@ -16,6 +16,8 @@
 
 import static com.google.gwt.event.dom.client.KeyCodes.KEY_ENTER;
 import static com.google.gwt.event.dom.client.KeyCodes.KEY_MAC_ENTER;
+import static java.util.stream.Collectors.collectingAndThen;
+import static java.util.stream.Collectors.toList;
 
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.changes.ChangeApi;
@@ -123,11 +125,15 @@
     this.lc = new LocalComments(project, psId.getParentKey());
     initWidget(uiBinder.createAndBindUi(this));
 
-    List<String> names = new ArrayList<>(permitted.keySet());
+    List<String> names =
+        permitted
+            .keySet()
+            .stream()
+            .sorted()
+            .collect(collectingAndThen(toList(), Collections::unmodifiableList));
     if (names.isEmpty()) {
       UIObject.setVisible(labelsParent, false);
     } else {
-      Collections.sort(names);
       renderLabels(names, all, permitted);
     }
 
@@ -439,8 +445,11 @@
               clp, project, psId, Util.C.commitMessage(), copyPath(Patch.MERGE_LIST, l)));
     }
 
-    List<String> paths = new ArrayList<>(m.keySet());
-    Collections.sort(paths);
+    List<String> paths =
+        m.keySet()
+            .stream()
+            .sorted()
+            .collect(collectingAndThen(toList(), Collections::unmodifiableList));
 
     for (String path : paths) {
       if (!Patch.isMagic(path)) {
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/AccountDashboardScreen.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/AccountDashboardScreen.java
index 495a3d4..7ec1102 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/AccountDashboardScreen.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/AccountDashboardScreen.java
@@ -178,7 +178,7 @@
       }
     }
 
-    Collections.sort(Natives.asList(out), outComparator());
+    Natives.asList(out).sort(outComparator());
 
     table.updateColumnsForLabels(wip, out, in, done);
     workInProgress.display(wip);
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/dashboards/DashboardsTable.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/dashboards/DashboardsTable.java
index 1a2f502..dcb9c01 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/dashboards/DashboardsTable.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/dashboards/DashboardsTable.java
@@ -27,7 +27,6 @@
 import com.google.gwt.user.client.ui.FlexTable.FlexCellFormatter;
 import com.google.gwt.user.client.ui.Image;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -76,7 +75,7 @@
       table.removeRow(table.getRowCount() - 1);
     }
 
-    Collections.sort(list, comparing(DashboardInfo::id));
+    list.sort(comparing(DashboardInfo::id));
 
     String ref = null;
     for (DashboardInfo d : list) {
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/CommentsCollections.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/CommentsCollections.java
index 5db62bd..2698584 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/CommentsCollections.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/CommentsCollections.java
@@ -29,7 +29,6 @@
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.user.client.rpc.AsyncCallback;
-import java.util.Collections;
 
 /** Collection of published and draft comments loaded from the server. */
 class CommentsCollections {
@@ -159,7 +158,7 @@
       for (CommentInfo c : Natives.asList(in)) {
         c.path(path);
       }
-      Collections.sort(Natives.asList(in), comparing(CommentInfo::updated));
+      Natives.asList(in).sort(comparing(CommentInfo::updated));
     }
     return in;
   }
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ProjectsTable.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ProjectsTable.java
index 74f04ff..3576b12 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ProjectsTable.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ProjectsTable.java
@@ -22,7 +22,6 @@
 import com.google.gerrit.client.rpc.Natives;
 import com.google.gwt.user.client.ui.FlexTable.FlexCellFormatter;
 import com.google.gwt.user.client.ui.Image;
-import java.util.Collections;
 import java.util.List;
 
 public class ProjectsTable extends NavigationTable<ProjectInfo> {
@@ -70,7 +69,7 @@
     }
 
     List<ProjectInfo> list = Natives.asList(projects.values());
-    Collections.sort(list, comparing(ProjectInfo::name));
+    list.sort(comparing(ProjectInfo::name));
     for (ProjectInfo p : list.subList(fromIndex, toIndex)) {
       insert(table.getRowCount(), p);
     }
diff --git a/gerrit-gwtui/src/main/java/net/codemirror/mode/ModeInfo.java b/gerrit-gwtui/src/main/java/net/codemirror/mode/ModeInfo.java
index ff12a07..9df066d 100644
--- a/gerrit-gwtui/src/main/java/net/codemirror/mode/ModeInfo.java
+++ b/gerrit-gwtui/src/main/java/net/codemirror/mode/ModeInfo.java
@@ -23,7 +23,6 @@
 import com.google.gwt.core.client.JsArrayString;
 import com.google.gwt.resources.client.DataResource;
 import com.google.gwt.safehtml.shared.SafeUri;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -243,7 +242,7 @@
         byMime.put(m.mode(), m);
       }
     }
-    Collections.sort(Natives.asList(filtered), comparing((ModeInfo m) -> m.name().toLowerCase()));
+    Natives.asList(filtered).sort(comparing(m -> m.name().toLowerCase()));
     setAll(filtered);
   }
 
diff --git a/java/com/google/gerrit/acceptance/HttpResponse.java b/java/com/google/gerrit/acceptance/HttpResponse.java
index b62e932..6c03793 100644
--- a/java/com/google/gerrit/acceptance/HttpResponse.java
+++ b/java/com/google/gerrit/acceptance/HttpResponse.java
@@ -14,6 +14,8 @@
 
 package com.google.gerrit.acceptance;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import com.google.common.base.Preconditions;
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -34,7 +36,7 @@
 
   public Reader getReader() throws IllegalStateException, IOException {
     if (reader == null && response.getEntity() != null) {
-      reader = new InputStreamReader(response.getEntity().getContent());
+      reader = new InputStreamReader(response.getEntity().getContent(), UTF_8);
     }
     return reader;
   }
diff --git a/java/com/google/gerrit/acceptance/SshSession.java b/java/com/google/gerrit/acceptance/SshSession.java
index 27dae3b..52d7f28 100644
--- a/java/com/google/gerrit/acceptance/SshSession.java
+++ b/java/com/google/gerrit/acceptance/SshSession.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.gerrit.acceptance.testsuite.account.TestSshKeys;
 import com.jcraft.jsch.ChannelExec;
@@ -54,10 +55,10 @@
       InputStream err = channel.getErrStream();
       channel.connect();
 
-      Scanner s = new Scanner(err).useDelimiter("\\A");
+      Scanner s = new Scanner(err, UTF_8.name()).useDelimiter("\\A");
       error = s.hasNext() ? s.next() : null;
 
-      s = new Scanner(in).useDelimiter("\\A");
+      s = new Scanner(in, UTF_8.name()).useDelimiter("\\A");
       return s.hasNext() ? s.next() : "";
     } finally {
       channel.disconnect();
diff --git a/java/com/google/gerrit/common/data/LabelType.java b/java/com/google/gerrit/common/data/LabelType.java
index 29fc9c7..ef10c22 100644
--- a/java/com/google/gerrit/common/data/LabelType.java
+++ b/java/com/google/gerrit/common/data/LabelType.java
@@ -17,13 +17,13 @@
 import static java.util.Comparator.comparing;
 import static java.util.stream.Collectors.collectingAndThen;
 import static java.util.stream.Collectors.toList;
-import static java.util.stream.Collectors.toMap;
 
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.reviewdb.client.LabelId;
 import com.google.gerrit.reviewdb.client.PatchSetApproval;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -142,12 +142,10 @@
     setCopyMinScore(DEF_COPY_MIN_SCORE);
     setAllowPostSubmit(DEF_ALLOW_POST_SUBMIT);
 
-    byValue =
-        values
-            .stream()
-            .collect(
-                collectingAndThen(
-                    toMap(LabelValue::getValue, v -> v), Collections::unmodifiableMap));
+    byValue = new HashMap<>();
+    for (LabelValue v : values) {
+      byValue.put(v.getValue(), v);
+    }
   }
 
   public String getName() {
diff --git a/java/com/google/gerrit/extensions/annotations/RemoveAfter.java b/java/com/google/gerrit/extensions/annotations/RemoveAfter.java
new file mode 100644
index 0000000..aa31dd0
--- /dev/null
+++ b/java/com/google/gerrit/extensions/annotations/RemoveAfter.java
@@ -0,0 +1,37 @@
+// Copyright (C) 2018 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.extensions.annotations;
+
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+import com.google.inject.BindingAnnotation;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for features that are deprecated, but still present to adhere to the one-release-grace
+ * period we promised to users.
+ */
+@Target({ElementType.PARAMETER, ElementType.FIELD, ElementType.METHOD, ElementType.TYPE})
+@Retention(SOURCE)
+@BindingAnnotation
+public @interface RemoveAfter {
+  /**
+   * Version after which the annotated functionality can be removed. Once the referenced version was
+   * branched off, the annotated code can be removed.
+   */
+  String value();
+}
diff --git a/java/com/google/gerrit/extensions/registration/DynamicSet.java b/java/com/google/gerrit/extensions/registration/DynamicSet.java
index df3560a..6b3a49b 100644
--- a/java/com/google/gerrit/extensions/registration/DynamicSet.java
+++ b/java/com/google/gerrit/extensions/registration/DynamicSet.java
@@ -168,7 +168,7 @@
 
   @Override
   public Iterator<T> iterator() {
-    Iterator<Entry<T>> entryIterator = entryIterator();
+    Iterator<Entry<T>> entryIterator = entries().iterator();
     return new Iterator<T>() {
       @Override
       public boolean hasNext() {
@@ -183,39 +183,44 @@
     };
   }
 
-  public Iterator<Entry<T>> entryIterator() {
+  public Iterable<Entry<T>> entries() {
     final Iterator<AtomicReference<NamedProvider<T>>> itr = items.iterator();
-    return new Iterator<Entry<T>>() {
-      private Entry<T> next;
-
+    return new Iterable<Entry<T>>() {
       @Override
-      public boolean hasNext() {
-        while (next == null && itr.hasNext()) {
-          NamedProvider<T> p = itr.next().get();
-          if (p != null) {
-            try {
-              next = new Entry<>(p.pluginName, p.impl);
-            } catch (RuntimeException e) {
-              // TODO Log failed member of DynamicSet.
+      public Iterator<Entry<T>> iterator() {
+        return new Iterator<Entry<T>>() {
+          private Entry<T> next;
+
+          @Override
+          public boolean hasNext() {
+            while (next == null && itr.hasNext()) {
+              NamedProvider<T> p = itr.next().get();
+              if (p != null) {
+                try {
+                  next = new Entry<>(p.pluginName, p.impl);
+                } catch (RuntimeException e) {
+                  // TODO Log failed member of DynamicSet.
+                }
+              }
             }
+            return next != null;
           }
-        }
-        return next != null;
-      }
 
-      @Override
-      public Entry<T> next() {
-        if (hasNext()) {
-          Entry<T> result = next;
-          next = null;
-          return result;
-        }
-        throw new NoSuchElementException();
-      }
+          @Override
+          public Entry<T> next() {
+            if (hasNext()) {
+              Entry<T> result = next;
+              next = null;
+              return result;
+            }
+            throw new NoSuchElementException();
+          }
 
-      @Override
-      public void remove() {
-        throw new UnsupportedOperationException();
+          @Override
+          public void remove() {
+            throw new UnsupportedOperationException();
+          }
+        };
       }
     };
   }
diff --git a/java/com/google/gerrit/httpd/GerritAuthModule.java b/java/com/google/gerrit/httpd/GerritAuthModule.java
new file mode 100644
index 0000000..c0ef207
--- /dev/null
+++ b/java/com/google/gerrit/httpd/GerritAuthModule.java
@@ -0,0 +1,55 @@
+// Copyright (C) 2018 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.httpd;
+
+import static com.google.gerrit.extensions.api.lfs.LfsDefinitions.LFS_URL_WO_AUTH_REGEX;
+
+import com.google.gerrit.extensions.client.GitBasicAuthPolicy;
+import com.google.gerrit.server.config.AuthConfig;
+import com.google.inject.Inject;
+import com.google.inject.servlet.ServletModule;
+import javax.servlet.Filter;
+
+/** Configures filter for authenticating REST requests. */
+public class GerritAuthModule extends ServletModule {
+  private static final String NOT_AUTHORIZED_LFS_URL_REGEX = "^(?:(?!/a/))" + LFS_URL_WO_AUTH_REGEX;
+  private final AuthConfig authConfig;
+
+  @Inject
+  GerritAuthModule(AuthConfig authConfig) {
+    this.authConfig = authConfig;
+  }
+
+  @Override
+  protected void configureServlets() {
+    Class<? extends Filter> authFilter = retreiveAuthFilterFromConfig(authConfig);
+
+    filterRegex(NOT_AUTHORIZED_LFS_URL_REGEX).through(authFilter);
+    filter("/a/*").through(authFilter);
+  }
+
+  static Class<? extends Filter> retreiveAuthFilterFromConfig(AuthConfig authConfig) {
+    Class<? extends Filter> authFilter;
+    if (authConfig.isTrustContainerAuth()) {
+      authFilter = ContainerAuthFilter.class;
+    } else {
+      authFilter =
+          authConfig.getGitBasicAuthPolicy() == GitBasicAuthPolicy.OAUTH
+              ? ProjectOAuthFilter.class
+              : ProjectBasicAuthFilter.class;
+    }
+    return authFilter;
+  }
+}
diff --git a/java/com/google/gerrit/httpd/GitOverHttpModule.java b/java/com/google/gerrit/httpd/GitOverHttpModule.java
index 3f3737d..8400d60 100644
--- a/java/com/google/gerrit/httpd/GitOverHttpModule.java
+++ b/java/com/google/gerrit/httpd/GitOverHttpModule.java
@@ -14,20 +14,16 @@
 
 package com.google.gerrit.httpd;
 
-import static com.google.gerrit.extensions.api.lfs.LfsDefinitions.LFS_URL_WO_AUTH_REGEX;
+import static com.google.gerrit.httpd.GitOverHttpServlet.URL_REGEX;
 
-import com.google.gerrit.extensions.client.GitBasicAuthPolicy;
 import com.google.gerrit.reviewdb.client.CoreDownloadSchemes;
 import com.google.gerrit.server.config.AuthConfig;
 import com.google.gerrit.server.config.DownloadConfig;
 import com.google.inject.Inject;
 import com.google.inject.servlet.ServletModule;
-import javax.servlet.Filter;
 
 /** Configures Git access over HTTP with authentication. */
 public class GitOverHttpModule extends ServletModule {
-  private static final String NOT_AUTHORIZED_LFS_URL_REGEX = "^(?:(?!/a/))" + LFS_URL_WO_AUTH_REGEX;
-
   private final AuthConfig authConfig;
   private final DownloadConfig downloadConfig;
 
@@ -39,28 +35,10 @@
 
   @Override
   protected void configureServlets() {
-    Class<? extends Filter> authFilter;
-    if (authConfig.isTrustContainerAuth()) {
-      authFilter = ContainerAuthFilter.class;
-    } else {
-      authFilter =
-          authConfig.getGitBasicAuthPolicy() == GitBasicAuthPolicy.OAUTH
-              ? ProjectOAuthFilter.class
-              : ProjectBasicAuthFilter.class;
+    if (downloadConfig.getDownloadSchemes().contains(CoreDownloadSchemes.ANON_HTTP)
+        || downloadConfig.getDownloadSchemes().contains(CoreDownloadSchemes.HTTP)) {
+      filterRegex(URL_REGEX).through(GerritAuthModule.retreiveAuthFilterFromConfig(authConfig));
+      serveRegex(URL_REGEX).with(GitOverHttpServlet.class);
     }
-
-    if (isHttpEnabled()) {
-      String git = GitOverHttpServlet.URL_REGEX;
-      filterRegex(git).through(authFilter);
-      serveRegex(git).with(GitOverHttpServlet.class);
-    }
-
-    filterRegex(NOT_AUTHORIZED_LFS_URL_REGEX).through(authFilter);
-    filter("/a/*").through(authFilter);
-  }
-
-  private boolean isHttpEnabled() {
-    return downloadConfig.getDownloadSchemes().contains(CoreDownloadSchemes.ANON_HTTP)
-        || downloadConfig.getDownloadSchemes().contains(CoreDownloadSchemes.HTTP);
   }
 }
diff --git a/java/com/google/gerrit/httpd/init/WebAppInitializer.java b/java/com/google/gerrit/httpd/init/WebAppInitializer.java
index 8e380f5..cb476af 100644
--- a/java/com/google/gerrit/httpd/init/WebAppInitializer.java
+++ b/java/com/google/gerrit/httpd/init/WebAppInitializer.java
@@ -23,6 +23,7 @@
 import com.google.gerrit.extensions.client.AuthType;
 import com.google.gerrit.gpg.GpgModule;
 import com.google.gerrit.httpd.AllRequestFilter;
+import com.google.gerrit.httpd.GerritAuthModule;
 import com.google.gerrit.httpd.GetUserFilter;
 import com.google.gerrit.httpd.GitOverHttpModule;
 import com.google.gerrit.httpd.H2CacheBasedWebSession;
@@ -422,9 +423,10 @@
   private Injector createWebInjector() {
     final List<Module> modules = new ArrayList<>();
     modules.add(RequestContextFilter.module());
-    modules.add(AllRequestFilter.module());
     modules.add(RequestMetricsFilter.module());
+    modules.add(sysInjector.getInstance(GerritAuthModule.class));
     modules.add(sysInjector.getInstance(GitOverHttpModule.class));
+    modules.add(AllRequestFilter.module());
     modules.add(sysInjector.getInstance(WebModule.class));
     modules.add(sysInjector.getInstance(RequireSslFilter.Module.class));
     if (sshInjector != null) {
diff --git a/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java b/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java
index 9a24e47..74cadd3 100644
--- a/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java
+++ b/java/com/google/gerrit/httpd/plugins/HttpPluginServlet.java
@@ -456,8 +456,8 @@
       }
     }
 
-    Collections.sort(cmds, PluginEntry.COMPARATOR_BY_NAME);
-    Collections.sort(docs, PluginEntry.COMPARATOR_BY_NAME);
+    cmds.sort(PluginEntry.COMPARATOR_BY_NAME);
+    docs.sort(PluginEntry.COMPARATOR_BY_NAME);
 
     StringBuilder md = new StringBuilder();
     md.append(String.format("# Plugin %s #\n", pluginName));
diff --git a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
index 0b01d0c..38fe0e2 100644
--- a/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -18,7 +18,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.collect.ImmutableSortedSet.toImmutableSortedSet;
 import static com.google.common.flogger.LazyArgs.lazy;
 import static com.google.common.net.HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS;
 import static com.google.common.net.HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS;
@@ -34,7 +33,6 @@
 import static java.math.RoundingMode.CEILING;
 import static java.nio.charset.StandardCharsets.ISO_8859_1;
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static java.util.Comparator.naturalOrder;
 import static java.util.stream.Collectors.joining;
 import static javax.servlet.http.HttpServletResponse.SC_ACCEPTED;
 import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
@@ -59,7 +57,6 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Lists;
@@ -292,10 +289,9 @@
 
     try (TraceContext traceContext = enableTracing(req, res)) {
       try (PerThreadCache ignored = PerThreadCache.create()) {
-        HttpServletRequest origReq = req;
         logger.atFinest().log(
             "Received REST request: %s %s (parameters: %s)",
-            req.getMethod(), req.getRequestURI(), lazy(() -> getParameterNames(origReq)));
+            req.getMethod(), req.getRequestURI(), getParameterNames(req));
         logger.atFinest().log("Calling user: %s", globals.currentUser.get().getLoggableName());
 
         if (isCorsPreflight(req)) {
@@ -1319,8 +1315,10 @@
     }
   }
 
-  private ImmutableSortedSet<String> getParameterNames(HttpServletRequest req) {
-    return req.getParameterMap().keySet().stream().collect(toImmutableSortedSet(naturalOrder()));
+  private List<String> getParameterNames(HttpServletRequest req) {
+    List<String> parameterNames = new ArrayList<>(req.getParameterMap().keySet());
+    Collections.sort(parameterNames);
+    return parameterNames;
   }
 
   private TraceContext enableTracing(HttpServletRequest req, HttpServletResponse res) {
diff --git a/java/com/google/gerrit/index/query/AndSource.java b/java/com/google/gerrit/index/query/AndSource.java
index e2605f4..d1e1c30 100644
--- a/java/com/google/gerrit/index/query/AndSource.java
+++ b/java/com/google/gerrit/index/query/AndSource.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.index.query;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
 
 import com.google.common.base.Throwables;
 import com.google.common.collect.FluentIterable;
@@ -26,7 +27,6 @@
 import com.google.gwtorm.server.ResultSet;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
@@ -175,10 +175,8 @@
     return cardinality;
   }
 
-  private List<Predicate<T>> sort(Collection<? extends Predicate<T>> that) {
-    List<Predicate<T>> r = new ArrayList<>(that);
-    Collections.sort(r, this);
-    return r;
+  private ImmutableList<Predicate<T>> sort(Collection<? extends Predicate<T>> that) {
+    return that.stream().sorted(this).collect(toImmutableList());
   }
 
   @Override
diff --git a/java/com/google/gerrit/pgm/Daemon.java b/java/com/google/gerrit/pgm/Daemon.java
index 517787c..1a9af55 100644
--- a/java/com/google/gerrit/pgm/Daemon.java
+++ b/java/com/google/gerrit/pgm/Daemon.java
@@ -26,6 +26,7 @@
 import com.google.gerrit.extensions.client.AuthType;
 import com.google.gerrit.gpg.GpgModule;
 import com.google.gerrit.httpd.AllRequestFilter;
+import com.google.gerrit.httpd.GerritAuthModule;
 import com.google.gerrit.httpd.GetUserFilter;
 import com.google.gerrit.httpd.GitOverHttpModule;
 import com.google.gerrit.httpd.H2CacheBasedWebSession;
@@ -575,10 +576,11 @@
       modules.add(new ProjectQoSFilter.Module());
     }
     modules.add(RequestContextFilter.module());
-    modules.add(AllRequestFilter.module());
     modules.add(RequestMetricsFilter.module());
     modules.add(H2CacheBasedWebSession.module());
+    modules.add(sysInjector.getInstance(GerritAuthModule.class));
     modules.add(sysInjector.getInstance(GitOverHttpModule.class));
+    modules.add(AllRequestFilter.module());
     modules.add(sysInjector.getInstance(WebModule.class));
     modules.add(sysInjector.getInstance(RequireSslFilter.Module.class));
     modules.add(new HttpPluginModule());
diff --git a/java/com/google/gerrit/pgm/init/InitPlugins.java b/java/com/google/gerrit/pgm/init/InitPlugins.java
index 7f55903..e43114c 100644
--- a/java/com/google/gerrit/pgm/init/InitPlugins.java
+++ b/java/com/google/gerrit/pgm/init/InitPlugins.java
@@ -30,7 +30,6 @@
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.jar.Attributes;
 import java.util.jar.JarFile;
@@ -66,7 +65,7 @@
           }
           result.add(new PluginData(pluginName, pluginVersion, tmpPlugin));
         });
-    Collections.sort(result, comparing(p -> p.name));
+    result.sort(comparing(p -> p.name));
     return result;
   }
 
diff --git a/java/com/google/gerrit/server/CommentsUtil.java b/java/com/google/gerrit/server/CommentsUtil.java
index 18d9b3d..99dfbbb 100644
--- a/java/com/google/gerrit/server/CommentsUtil.java
+++ b/java/com/google/gerrit/server/CommentsUtil.java
@@ -502,7 +502,7 @@
   }
 
   private static <T extends Comment> List<T> sort(List<T> comments) {
-    Collections.sort(comments, COMMENT_ORDER);
+    comments.sort(COMMENT_ORDER);
     return comments;
   }
 
diff --git a/java/com/google/gerrit/server/change/WalkSorter.java b/java/com/google/gerrit/server/change/WalkSorter.java
index cff1ac7..916a62b 100644
--- a/java/com/google/gerrit/server/change/WalkSorter.java
+++ b/java/com/google/gerrit/server/change/WalkSorter.java
@@ -34,7 +34,6 @@
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Deque;
 import java.util.HashSet;
 import java.util.List;
@@ -110,7 +109,7 @@
     for (Map.Entry<Project.NameKey, Collection<ChangeData>> e : byProject.asMap().entrySet()) {
       sortedByProject.add(sortProject(e.getKey(), e.getValue()));
     }
-    Collections.sort(sortedByProject, PROJECT_LIST_SORTER);
+    sortedByProject.sort(PROJECT_LIST_SORTER);
     return Iterables.concat(sortedByProject);
   }
 
diff --git a/java/com/google/gerrit/server/events/EventFactory.java b/java/com/google/gerrit/server/events/EventFactory.java
index 2fbc1c7..fbce4b2 100644
--- a/java/com/google/gerrit/server/events/EventFactory.java
+++ b/java/com/google/gerrit/server/events/EventFactory.java
@@ -73,7 +73,6 @@
 import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -329,10 +328,9 @@
       }
     }
     // Sort by original parent order.
-    Collections.sort(
-        ca.dependsOn,
+    ca.dependsOn.sort(
         comparing(
-            (DependencyAttribute d) -> {
+            d -> {
               for (int i = 0; i < parentNames.size(); i++) {
                 if (parentNames.get(i).equals(d.revision)) {
                   return i;
diff --git a/java/com/google/gerrit/server/git/MergeUtil.java b/java/com/google/gerrit/server/git/MergeUtil.java
index 0231378..686be19 100644
--- a/java/com/google/gerrit/server/git/MergeUtil.java
+++ b/java/com/google/gerrit/server/git/MergeUtil.java
@@ -220,7 +220,7 @@
     } catch (IOException e) {
       throw new IntegrationException("Branch head sorting failed", e);
     }
-    Collections.sort(result, CodeReviewCommit.ORDER);
+    result.sort(CodeReviewCommit.ORDER);
     return result;
   }
 
diff --git a/java/com/google/gerrit/server/git/meta/TabFile.java b/java/com/google/gerrit/server/git/meta/TabFile.java
index ef25cd8..4c0378a 100644
--- a/java/com/google/gerrit/server/git/meta/TabFile.java
+++ b/java/com/google/gerrit/server/git/meta/TabFile.java
@@ -14,13 +14,15 @@
 
 package com.google.gerrit.server.git.meta;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.server.git.ValidationError;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.StringReader;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -122,10 +124,8 @@
     return buf.toString();
   }
 
-  protected static <T extends Comparable<? super T>> List<T> sort(Collection<T> m) {
-    ArrayList<T> r = new ArrayList<>(m);
-    Collections.sort(r);
-    return r;
+  protected static <T extends Comparable<? super T>> ImmutableList<T> sort(Collection<T> m) {
+    return m.stream().sorted().collect(toImmutableList());
   }
 
   protected static String pad(int len, String src) {
diff --git a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
index b986f90..e9093cc 100644
--- a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
+++ b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
@@ -1810,7 +1810,7 @@
       return;
     }
 
-    if (validateConnected(magicBranch.dest, tip)) {
+    if (validateConnected(magicBranch.cmd, magicBranch.dest, tip)) {
       this.magicBranch = magicBranch;
     }
   }
@@ -1819,7 +1819,7 @@
   // branch.  If they aren't, we want to abort. We do this check by
   // looking to see if we can compute a merge base between the new
   // commits and the target branch head.
-  private boolean validateConnected(Branch.NameKey dest, RevCommit tip) {
+  private boolean validateConnected(ReceiveCommand cmd, Branch.NameKey dest, RevCommit tip) {
     RevWalk walk = receivePack.getRevWalk();
     try {
       Ref targetRef = receivePack.getAdvertisedRefs().get(dest.get());
@@ -1842,7 +1842,7 @@
         walk.markStart(tip);
         walk.markStart(h);
         if (walk.next() == null) {
-          reject(magicBranch.cmd, "no common ancestry");
+          reject(cmd, "no common ancestry");
           return false;
         }
       } finally {
@@ -1850,7 +1850,7 @@
         walk.setRevFilter(oldRevFilter);
       }
     } catch (IOException e) {
-      magicBranch.cmd.setResult(REJECTED_MISSING_OBJECT);
+      cmd.setResult(REJECTED_MISSING_OBJECT);
       logger.atSevere().withCause(e).log("Invalid pack upload; one or more objects weren't sent");
       return false;
     }
diff --git a/java/com/google/gerrit/server/mail/send/CommentSender.java b/java/com/google/gerrit/server/mail/send/CommentSender.java
index 54176e2..0baaa11c 100644
--- a/java/com/google/gerrit/server/mail/send/CommentSender.java
+++ b/java/com/google/gerrit/server/mail/send/CommentSender.java
@@ -239,7 +239,7 @@
       }
     }
 
-    Collections.sort(groups, Comparator.comparing(g -> g.filename, FilenameComparator.INSTANCE));
+    groups.sort(Comparator.comparing(g -> g.filename, FilenameComparator.INSTANCE));
     return groups;
   }
 
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
index 4eeab81..cbb7020 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
@@ -79,7 +79,6 @@
 import java.sql.Timestamp;
 import java.text.ParseException;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -297,9 +296,7 @@
       }
       result.put(a.getPatchSetId(), a);
     }
-    for (Collection<PatchSetApproval> v : result.asMap().values()) {
-      Collections.sort((List<PatchSetApproval>) v, ChangeNotes.PSA_BY_TIME);
-    }
+    result.keySet().forEach(k -> result.get(k).sort(ChangeNotes.PSA_BY_TIME));
     return result;
   }
 
diff --git a/java/com/google/gerrit/server/notedb/LegacyChangeNoteWrite.java b/java/com/google/gerrit/server/notedb/LegacyChangeNoteWrite.java
index 7931d88..c9711b5 100644
--- a/java/com/google/gerrit/server/notedb/LegacyChangeNoteWrite.java
+++ b/java/com/google/gerrit/server/notedb/LegacyChangeNoteWrite.java
@@ -15,10 +15,12 @@
 package com.google.gerrit.server.notedb;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.gerrit.server.CommentsUtil.COMMENT_ORDER;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ListMultimap;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Comment;
@@ -30,8 +32,6 @@
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.sql.Timestamp;
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Date;
 import java.util.List;
 import org.eclipse.jgit.lib.PersonIdent;
@@ -87,8 +87,7 @@
       return;
     }
 
-    List<Integer> psIds = new ArrayList<>(comments.keySet());
-    Collections.sort(psIds);
+    ImmutableList<Integer> psIds = comments.keySet().stream().sorted().collect(toImmutableList());
 
     OutputStreamWriter streamWriter = new OutputStreamWriter(out, UTF_8);
     try (PrintWriter writer = new PrintWriter(streamWriter)) {
diff --git a/java/com/google/gerrit/server/patch/DiffSummaryLoader.java b/java/com/google/gerrit/server/patch/DiffSummaryLoader.java
index 8bca19f..9153638 100644
--- a/java/com/google/gerrit/server/patch/DiffSummaryLoader.java
+++ b/java/com/google/gerrit/server/patch/DiffSummaryLoader.java
@@ -19,7 +19,6 @@
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Callable;
 
@@ -66,8 +65,9 @@
           break;
       }
     }
-    Collections.sort(r);
     return new DiffSummary(
-        r.toArray(new String[r.size()]), patchList.getInsertions(), patchList.getDeletions());
+        r.stream().sorted().toArray(String[]::new),
+        patchList.getInsertions(),
+        patchList.getDeletions());
   }
 }
diff --git a/java/com/google/gerrit/server/patch/PatchScriptBuilder.java b/java/com/google/gerrit/server/patch/PatchScriptBuilder.java
index e94f7e8..61f0180 100644
--- a/java/com/google/gerrit/server/patch/PatchScriptBuilder.java
+++ b/java/com/google/gerrit/server/patch/PatchScriptBuilder.java
@@ -35,7 +35,6 @@
 import eu.medsea.mimeutil.MimeUtil2;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Optional;
@@ -364,7 +363,7 @@
     // them correctly later.
     //
     edits.addAll(empty);
-    Collections.sort(edits, EDIT_SORT);
+    edits.sort(EDIT_SORT);
   }
 
   private void safeAdd(List<Edit> empty, Edit toAdd) {
diff --git a/java/com/google/gerrit/server/permissions/SectionSortCache.java b/java/com/google/gerrit/server/permissions/SectionSortCache.java
index 48c8bff..e5392b0 100644
--- a/java/com/google/gerrit/server/permissions/SectionSortCache.java
+++ b/java/com/google/gerrit/server/permissions/SectionSortCache.java
@@ -26,7 +26,6 @@
 import com.google.inject.Singleton;
 import com.google.inject.name.Named;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.IdentityHashMap;
 import java.util.List;
 
@@ -88,7 +87,7 @@
         poison |= srcMap.put(sections.get(i), i) != null;
       }
 
-      Collections.sort(sections, new MostSpecificComparator(ref));
+      sections.sort(new MostSpecificComparator(ref));
 
       int[] srcIdx;
       if (isIdentityTransform(sections, srcMap)) {
diff --git a/java/com/google/gerrit/server/project/ProjectConfig.java b/java/com/google/gerrit/server/project/ProjectConfig.java
index 60c9ffd..5b79ab9 100644
--- a/java/com/google/gerrit/server/project/ProjectConfig.java
+++ b/java/com/google/gerrit/server/project/ProjectConfig.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.server.project;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.gerrit.common.data.Permission.isPermission;
 import static com.google.gerrit.reviewdb.client.Project.DEFAULT_SUBMIT_TYPE;
 import static java.util.stream.Collectors.toList;
@@ -1451,10 +1452,8 @@
     validationErrors.add(error);
   }
 
-  private static <T extends Comparable<? super T>> List<T> sort(Collection<T> m) {
-    ArrayList<T> r = new ArrayList<>(m);
-    Collections.sort(r);
-    return r;
+  private static <T extends Comparable<? super T>> ImmutableList<T> sort(Collection<T> m) {
+    return m.stream().sorted().collect(toImmutableList());
   }
 
   public boolean hasLegacyPermissions() {
diff --git a/java/com/google/gerrit/server/restapi/change/CommentJson.java b/java/com/google/gerrit/server/restapi/change/CommentJson.java
index 742fe16..a562592 100644
--- a/java/com/google/gerrit/server/restapi/change/CommentJson.java
+++ b/java/com/google/gerrit/server/restapi/change/CommentJson.java
@@ -37,7 +37,6 @@
 import com.google.gerrit.server.permissions.PermissionBackendException;
 import com.google.inject.Inject;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
@@ -98,9 +97,7 @@
         list.add(o);
       }
 
-      for (List<T> list : out.values()) {
-        Collections.sort(list, COMMENT_INFO_ORDER);
-      }
+      out.values().forEach(l -> l.sort(COMMENT_INFO_ORDER));
 
       if (loader != null) {
         loader.fill();
diff --git a/java/com/google/gerrit/server/restapi/change/ListRevisionDrafts.java b/java/com/google/gerrit/server/restapi/change/ListRevisionDrafts.java
index db8ef0c..dbd0ccf 100644
--- a/java/com/google/gerrit/server/restapi/change/ListRevisionDrafts.java
+++ b/java/com/google/gerrit/server/restapi/change/ListRevisionDrafts.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.restapi.change;
 
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.extensions.common.CommentInfo;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.Comment;
@@ -61,7 +62,7 @@
         .format(listComments(rsrc));
   }
 
-  public List<CommentInfo> getComments(RevisionResource rsrc)
+  public ImmutableList<CommentInfo> getComments(RevisionResource rsrc)
       throws OrmException, PermissionBackendException {
     return commentJson
         .get()
diff --git a/java/com/google/gerrit/server/restapi/change/ListRobotComments.java b/java/com/google/gerrit/server/restapi/change/ListRobotComments.java
index 66138ab..99366aa 100644
--- a/java/com/google/gerrit/server/restapi/change/ListRobotComments.java
+++ b/java/com/google/gerrit/server/restapi/change/ListRobotComments.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.restapi.change;
 
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.extensions.common.RobotCommentInfo;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.RobotComment;
@@ -52,7 +53,7 @@
         .format(listComments(rsrc));
   }
 
-  public List<RobotCommentInfo> getComments(RevisionResource rsrc)
+  public ImmutableList<RobotCommentInfo> getComments(RevisionResource rsrc)
       throws OrmException, PermissionBackendException {
     return commentJson
         .get()
diff --git a/java/com/google/gerrit/server/restapi/group/GetAuditLog.java b/java/com/google/gerrit/server/restapi/group/GetAuditLog.java
index 7af4284..dcdd8a8 100644
--- a/java/com/google/gerrit/server/restapi/group/GetAuditLog.java
+++ b/java/com/google/gerrit/server/restapi/group/GetAuditLog.java
@@ -41,7 +41,6 @@
 import com.google.inject.Singleton;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import org.eclipse.jgit.errors.ConfigInvalidException;
@@ -138,7 +137,7 @@
     accountLoader.fill();
 
     // sort by date and then reverse so that the newest audit event comes first
-    Collections.sort(auditEvents, comparing((GroupAuditEventInfo a) -> a.date).reversed());
+    auditEvents.sort(comparing((GroupAuditEventInfo a) -> a.date).reversed());
     return auditEvents;
   }
 }
diff --git a/java/com/google/gerrit/server/restapi/group/ListSubgroups.java b/java/com/google/gerrit/server/restapi/group/ListSubgroups.java
index 26b6db4..864b01b 100644
--- a/java/com/google/gerrit/server/restapi/group/ListSubgroups.java
+++ b/java/com/google/gerrit/server/restapi/group/ListSubgroups.java
@@ -30,7 +30,6 @@
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 @Singleton
@@ -72,8 +71,7 @@
         continue;
       }
     }
-    Collections.sort(
-        included,
+    included.sort(
         comparing((GroupInfo g) -> nullToEmpty(g.name)).thenComparing(g -> nullToEmpty(g.id)));
     return included;
   }
diff --git a/java/com/google/gerrit/server/restapi/project/ListBranches.java b/java/com/google/gerrit/server/restapi/project/ListBranches.java
index bf4a547..a0d2528 100644
--- a/java/com/google/gerrit/server/restapi/project/ListBranches.java
+++ b/java/com/google/gerrit/server/restapi/project/ListBranches.java
@@ -46,7 +46,6 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Set;
@@ -226,7 +225,7 @@
         // Do nothing.
       }
     }
-    Collections.sort(branches, new BranchComparator());
+    branches.sort(new BranchComparator());
     return branches;
   }
 
diff --git a/java/com/google/gerrit/server/restapi/project/ListTags.java b/java/com/google/gerrit/server/restapi/project/ListTags.java
index 578fbf3..f59e984 100644
--- a/java/com/google/gerrit/server/restapi/project/ListTags.java
+++ b/java/com/google/gerrit/server/restapi/project/ListTags.java
@@ -40,7 +40,6 @@
 import java.io.IOException;
 import java.sql.Timestamp;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import org.eclipse.jgit.errors.RepositoryNotFoundException;
@@ -135,7 +134,7 @@
       }
     }
 
-    Collections.sort(tags, comparing(t -> t.ref));
+    tags.sort(comparing(t -> t.ref));
 
     return new RefFilter<TagInfo>(Constants.R_TAGS)
         .start(start)
diff --git a/java/com/google/gerrit/server/submit/SubmitStrategyOp.java b/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
index 290e917..51dad5b 100644
--- a/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
+++ b/java/com/google/gerrit/server/submit/SubmitStrategyOp.java
@@ -53,7 +53,6 @@
 import com.google.gwtorm.server.OrmException;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -184,8 +183,7 @@
         continue; // Bogus ref, can't be merged into tip so we don't care.
       }
     }
-    Collections.sort(
-        commits,
+    commits.sort(
         ReviewDbUtil.intKeyOrdering().reverse().onResultOf(CodeReviewCommit::getPatchsetId));
     CodeReviewCommit result = MergeUtil.findAnyMergedInto(rw, commits, tip);
     if (result == null) {
diff --git a/java/com/google/gerrit/sshd/commands/ShowConnections.java b/java/com/google/gerrit/sshd/commands/ShowConnections.java
index 9b517c6..baadf02 100644
--- a/java/com/google/gerrit/sshd/commands/ShowConnections.java
+++ b/java/com/google/gerrit/sshd/commands/ShowConnections.java
@@ -15,8 +15,10 @@
 package com.google.gerrit.sshd.commands;
 
 import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.gerrit.sshd.CommandMetaData.Mode.MASTER_OR_SLAVE;
 
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.common.data.GlobalCapability;
 import com.google.gerrit.extensions.annotations.RequiresCapability;
@@ -33,11 +35,7 @@
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.text.SimpleDateFormat;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.Date;
-import java.util.List;
 import java.util.Optional;
 import org.apache.sshd.common.io.IoAcceptor;
 import org.apache.sshd.common.io.IoSession;
@@ -92,25 +90,27 @@
       throw new Failure(1, "fatal: sshd no longer running");
     }
 
-    final List<IoSession> list = new ArrayList<>(acceptor.getManagedSessions().values());
-    Collections.sort(
-        list,
-        new Comparator<IoSession>() {
-          @Override
-          public int compare(IoSession arg0, IoSession arg1) {
-            if (arg0 instanceof MinaSession) {
-              MinaSession mArg0 = (MinaSession) arg0;
-              MinaSession mArg1 = (MinaSession) arg1;
-              if (mArg0.getSession().getCreationTime() < mArg1.getSession().getCreationTime()) {
-                return -1;
-              } else if (mArg0.getSession().getCreationTime()
-                  > mArg1.getSession().getCreationTime()) {
-                return 1;
-              }
-            }
-            return (int) (arg0.getId() - arg1.getId());
-          }
-        });
+    final ImmutableList<IoSession> list =
+        acceptor
+            .getManagedSessions()
+            .values()
+            .stream()
+            .sorted(
+                (arg0, arg1) -> {
+                  if (arg0 instanceof MinaSession) {
+                    MinaSession mArg0 = (MinaSession) arg0;
+                    MinaSession mArg1 = (MinaSession) arg1;
+                    if (mArg0.getSession().getCreationTime()
+                        < mArg1.getSession().getCreationTime()) {
+                      return -1;
+                    } else if (mArg0.getSession().getCreationTime()
+                        > mArg1.getSession().getCreationTime()) {
+                      return 1;
+                    }
+                  }
+                  return (int) (arg0.getId() - arg1.getId());
+                })
+            .collect(toImmutableList());
 
     hostNameWidth = wide ? Integer.MAX_VALUE : columns - 9 - 9 - 10 - 32;
 
diff --git a/javatests/com/google/gerrit/acceptance/git/AbstractPushForReview.java b/javatests/com/google/gerrit/acceptance/git/AbstractPushForReview.java
index 7ad34a6..f1e67c1 100644
--- a/javatests/com/google/gerrit/acceptance/git/AbstractPushForReview.java
+++ b/javatests/com/google/gerrit/acceptance/git/AbstractPushForReview.java
@@ -213,6 +213,24 @@
   }
 
   @Test
+  @TestProjectInput(createEmptyCommit = false)
+  public void validateConnected() throws Exception {
+    RevCommit c = testRepo.commit().message("Initial commit").insertChangeId().create();
+    testRepo.reset(c);
+
+    String r = "refs/heads/master";
+    PushResult pr = pushHead(testRepo, r, false);
+    assertPushOk(pr, r);
+
+    RevCommit amended =
+        testRepo.amend(c).message("different initial commit").insertChangeId().create();
+    testRepo.reset(amended);
+    r = "refs/for/master";
+    pr = pushHead(testRepo, r, false);
+    assertPushRejected(pr, r, "no common ancestry");
+  }
+
+  @Test
   public void pushInitialCommitForRefsMetaConfigBranch() throws Exception {
     // delete refs/meta/config
     try (Repository repo = repoManager.openRepository(project);
diff --git a/javatests/com/google/gerrit/extensions/registration/DynamicSetTest.java b/javatests/com/google/gerrit/extensions/registration/DynamicSetTest.java
index bbcee2d..c86160f 100644
--- a/javatests/com/google/gerrit/extensions/registration/DynamicSetTest.java
+++ b/javatests/com/google/gerrit/extensions/registration/DynamicSetTest.java
@@ -123,7 +123,7 @@
     ds.add("bar", 2);
     ds.add("bar", 3);
 
-    Iterator<DynamicSet.Entry<Integer>> entryIterator = ds.entryIterator();
+    Iterator<DynamicSet.Entry<Integer>> entryIterator = ds.entries().iterator();
     DynamicSet.Entry<Integer> next = entryIterator.next();
     assertThat(next.getPluginName()).isEqualTo("foo");
     assertThat(next.getProvider().get()).isEqualTo(1);
diff --git a/javatests/com/google/gerrit/gpg/PushCertificateCheckerTest.java b/javatests/com/google/gerrit/gpg/PushCertificateCheckerTest.java
index ad8f4311..266f868 100644
--- a/javatests/com/google/gerrit/gpg/PushCertificateCheckerTest.java
+++ b/javatests/com/google/gerrit/gpg/PushCertificateCheckerTest.java
@@ -184,7 +184,7 @@
     }
 
     String cert = payload + new String(bout.toByteArray(), UTF_8);
-    Reader reader = new InputStreamReader(new ByteArrayInputStream(cert.getBytes(UTF_8)));
+    Reader reader = new InputStreamReader(new ByteArrayInputStream(cert.getBytes(UTF_8)), UTF_8);
     PushCertificateParser parser = new PushCertificateParser(repo, signedPushConfig);
     return parser.parse(reader);
   }
diff --git a/plugins/BUILD b/plugins/BUILD
index b7364be..8b9f4de 100644
--- a/plugins/BUILD
+++ b/plugins/BUILD
@@ -38,6 +38,7 @@
     "//java/com/google/gerrit/metrics/dropwizard",
     "//java/com/google/gerrit/reviewdb:server",
     "//java/com/google/gerrit/server/audit",
+    "//java/com/google/gerrit/server/schema",
     "//java/com/google/gerrit/util/http",
     "//lib/commons:compress",
     "//lib/commons:dbcp",
diff --git a/plugins/replication b/plugins/replication
index b62f006..d557ccc 160000
--- a/plugins/replication
+++ b/plugins/replication
@@ -1 +1 @@
-Subproject commit b62f006b1350180de0af02c82fb18fb290a2548f
+Subproject commit d557ccc642c59a55750f560ce0d98870e1550d65
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
index e905e038..ebd72ad 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js
@@ -122,7 +122,7 @@
       _changeComments: Object,
       _canStartReview: {
         type: Boolean,
-        computed: '_computeCanStartReview(_loggedIn, _change, _account)',
+        computed: '_computeCanStartReview(_change)',
       },
       _comments: Object,
       /** @type {?} */
@@ -1341,9 +1341,9 @@
       });
     },
 
-    _computeCanStartReview(loggedIn, change, account) {
-      return !!(loggedIn && change.work_in_progress &&
-          change.owner._account_id === account._account_id);
+    _computeCanStartReview(change) {
+      return !!(change.actions && change.actions.ready &&
+          change.actions.ready.enabled);
     },
 
     _computeReplyDisabled() { return false; },
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
index b5b8cd9..4e6cb6e 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html
@@ -1411,18 +1411,24 @@
       });
 
       test('canStartReview computation', () => {
-        const account1 = {_account_id: 1};
-        const account2 = {_account_id: 2};
-        const change = {
-          owner: {_account_id: 1},
+        const change1 = {};
+        const change2 = {
+          actions: {
+            ready: {
+              enabled: true,
+            },
+          },
         };
-        assert.isFalse(element._computeCanStartReview(true, change, account1));
-        change.work_in_progress = false;
-        assert.isFalse(element._computeCanStartReview(true, change, account1));
-        change.work_in_progress = true;
-        assert.isTrue(element._computeCanStartReview(true, change, account1));
-        assert.isFalse(element._computeCanStartReview(false, change, account1));
-        assert.isFalse(element._computeCanStartReview(true, change, account2));
+        const change3 = {
+          actions: {
+            ready: {
+              label: 'Ready for Review',
+            },
+          },
+        };
+        assert.isFalse(element._computeCanStartReview(change1));
+        assert.isTrue(element._computeCanStartReview(change2));
+        assert.isFalse(element._computeCanStartReview(change3));
       });
     });
 
diff --git a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
index 4f0a73b..9f1b412 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
@@ -96,7 +96,10 @@
         reflectToAttribute: true,
       },
       noRenderOnPrefsChange: Boolean,
-      comments: Object,
+      comments: {
+        type: Object,
+        value: {left: [], right: []},
+      },
       lineWrapping: {
         type: Boolean,
         value: false,