diff --git a/Documentation/intro-gerrit-walkthrough.txt b/Documentation/intro-gerrit-walkthrough.txt
index 1fba1dc..b4f799c2 100644
--- a/Documentation/intro-gerrit-walkthrough.txt
+++ b/Documentation/intro-gerrit-walkthrough.txt
@@ -28,7 +28,7 @@
 modify. To get this code, he runs the following `git clone` command:
 
 ----
-clone ssh://gerrithost:29418/RecipeBook.git RecipeBook
+git clone ssh://gerrithost:29418/RecipeBook.git RecipeBook
 ----
 
 After he clones the repository, he runs a couple of commands to add a
diff --git a/Documentation/rest-api-projects.txt b/Documentation/rest-api-projects.txt
index f69c4ae..76151b4 100644
--- a/Documentation/rest-api-projects.txt
+++ b/Documentation/rest-api-projects.txt
@@ -3058,12 +3058,12 @@
 |Field Name |        |Description
 |`match`    |        |A JavaScript regular expression to match
 positions to be replaced with a hyperlink, as documented in
-link#config-gerrit.html#commentlink.name.match[commentlink.name.match].
+link:config-gerrit.html#commentlink.name.match[commentlink.name.match].
 |`link`     |        |The URL to direct the user to whenever the
 regular expression is matched, as documented in
-link#config-gerrit.html#commentlink.name.link[commentlink.name.link].
+link:config-gerrit.html#commentlink.name.link[commentlink.name.link].
 |`enabled`  |optional|Whether the commentlink is enabled, as documented
-in link#config-gerrit.html#commentlink.name.enabled[
+in link:config-gerrit.html#commentlink.name.enabled[
 commentlink.name.enabled]. If not set the commentlink is enabled.
 |==================================================
 
diff --git a/java/com/google/gerrit/json/BUILD b/java/com/google/gerrit/json/BUILD
index 7282dc4..030dddc 100644
--- a/java/com/google/gerrit/json/BUILD
+++ b/java/com/google/gerrit/json/BUILD
@@ -4,5 +4,6 @@
     visibility = ["//visibility:public"],
     deps = [
         "//lib:gson",
+        "//lib/flogger:api",
     ],
 )
diff --git a/java/com/google/gerrit/json/EnumTypeAdapterFactory.java b/java/com/google/gerrit/json/EnumTypeAdapterFactory.java
new file mode 100644
index 0000000..dc74f67
--- /dev/null
+++ b/java/com/google/gerrit/json/EnumTypeAdapterFactory.java
@@ -0,0 +1,78 @@
+// Copyright (C) 2019 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.json;
+
+import com.google.common.flogger.FluentLogger;
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.internal.bind.TypeAdapters;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+
+/**
+ * A {@code TypeAdapterFactory} for enums.
+ *
+ * <p>This factory introduces a wrapper around Gson's own default enum handler to add the following
+ * special behavior: log when input which doesn't match any existing enum value is encountered.
+ */
+public class EnumTypeAdapterFactory implements TypeAdapterFactory {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  @SuppressWarnings({"unchecked"})
+  @Override
+  public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
+    TypeAdapter<T> defaultEnumAdapter = TypeAdapters.ENUM_FACTORY.create(gson, typeToken);
+    if (defaultEnumAdapter == null) {
+      // Not an enum. -> Enum type adapter doesn't apply.
+      return null;
+    }
+
+    return (TypeAdapter<T>) new EnumTypeAdapter(defaultEnumAdapter, typeToken);
+  }
+
+  private static class EnumTypeAdapter<T extends Enum<T>> extends TypeAdapter<T> {
+
+    private final TypeAdapter<T> defaultEnumAdapter;
+    private final TypeToken<T> typeToken;
+
+    public EnumTypeAdapter(TypeAdapter<T> defaultEnumAdapter, TypeToken<T> typeToken) {
+      this.defaultEnumAdapter = defaultEnumAdapter;
+      this.typeToken = typeToken;
+    }
+
+    @Override
+    public T read(JsonReader in) throws IOException {
+      // Still handle null values. -> Check them first.
+      if (in.peek() == JsonToken.NULL) {
+        in.nextNull();
+        return null;
+      }
+      T enumValue = defaultEnumAdapter.read(in);
+      if (enumValue == null) {
+        logger.atWarning().log("Expected an existing value for enum %s.", typeToken);
+      }
+      return enumValue;
+    }
+
+    @Override
+    public void write(JsonWriter out, T value) throws IOException {
+      defaultEnumAdapter.write(out, value);
+    }
+  }
+}
diff --git a/java/com/google/gerrit/json/OutputFormat.java b/java/com/google/gerrit/json/OutputFormat.java
index a2d174f..3e7c319 100644
--- a/java/com/google/gerrit/json/OutputFormat.java
+++ b/java/com/google/gerrit/json/OutputFormat.java
@@ -55,7 +55,8 @@
     GsonBuilder gb =
         new GsonBuilder()
             .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
-            .registerTypeAdapter(Timestamp.class, new SqlTimestampDeserializer());
+            .registerTypeAdapter(Timestamp.class, new SqlTimestampDeserializer())
+            .registerTypeAdapterFactory(new EnumTypeAdapterFactory());
     if (this == OutputFormat.JSON) {
       gb.setPrettyPrinting();
     }
diff --git a/java/com/google/gerrit/server/account/externalids/ExternalIdCacheLoader.java b/java/com/google/gerrit/server/account/externalids/ExternalIdCacheLoader.java
index 21bbbd2..68841da 100644
--- a/java/com/google/gerrit/server/account/externalids/ExternalIdCacheLoader.java
+++ b/java/com/google/gerrit/server/account/externalids/ExternalIdCacheLoader.java
@@ -63,9 +63,6 @@
   // Maximum number of prior states we inspect to find a base for differential. If no cached state
   // is found within this number of parents, we fall back to reading everything from scratch.
   private static final int MAX_HISTORY_LOOKBACK = 10;
-  // Maximum number of changes we perform using the differential approach. If more updates need to
-  // be applied, we fall back to reading everything from scratch.
-  private static final int MAX_DIFF_UPDATES = 50;
 
   private final ExternalIdReader externalIdReader;
   private final Provider<Cache<ObjectId, AllExternalIds>> externalIdCache;
diff --git a/java/com/google/gerrit/server/plugincontext/PluginContext.java b/java/com/google/gerrit/server/plugincontext/PluginContext.java
index 266eb92..90d56c8 100644
--- a/java/com/google/gerrit/server/plugincontext/PluginContext.java
+++ b/java/com/google/gerrit/server/plugincontext/PluginContext.java
@@ -272,7 +272,7 @@
       Throwables.throwIfUnchecked(e);
       pluginMetrics.incrementErrorCount(extension);
       logger.atWarning().withCause(e).log(
-          "Failure in %s of plugin invoke%s", extensionImpl.getClass(), extension.getPluginName());
+          "Failure in %s of plugin %s", extensionImpl.getClass(), extension.getPluginName());
     }
   }
 
diff --git a/java/com/google/gerrit/server/update/RetryHelper.java b/java/com/google/gerrit/server/update/RetryHelper.java
index 695feba..f50f857 100644
--- a/java/com/google/gerrit/server/update/RetryHelper.java
+++ b/java/com/google/gerrit/server/update/RetryHelper.java
@@ -291,7 +291,7 @@
                       .addTag(RequestId.Type.TRACE_ID, "retry-on-failure-" + new RequestId())
                       .forceLogging();
                   logger.atFine().withCause(t).log(
-                      "%s failed, retry with tracing eanbled",
+                      "%s failed, retry with tracing enabled",
                       opts.caller().map(Class::getSimpleName).orElse("N/A"));
                   return true;
                 }
diff --git a/javatests/com/google/gerrit/json/JsonEnumMappingTest.java b/javatests/com/google/gerrit/json/JsonEnumMappingTest.java
new file mode 100644
index 0000000..6e57b01
--- /dev/null
+++ b/javatests/com/google/gerrit/json/JsonEnumMappingTest.java
@@ -0,0 +1,84 @@
+// Copyright (C) 2019 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.json;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gson.Gson;
+import org.junit.Test;
+
+public class JsonEnumMappingTest {
+
+  // Use the regular, pre-configured Gson object we use throughout the Gerrit server to ensure that
+  // the EnumTypeAdapterFactory is properly set up.
+  private final Gson gson = OutputFormat.JSON.newGson();
+
+  @Test
+  public void nullCanBeWrittenAndParsedBack() {
+    String resultingJson = gson.toJson(null, TestEnum.class);
+    TestEnum value = gson.fromJson(resultingJson, TestEnum.class);
+    assertThat(value).isNull();
+  }
+
+  @Test
+  public void enumValueCanBeWrittenAndParsedBack() {
+    String resultingJson = gson.toJson(TestEnum.ONE, TestEnum.class);
+    TestEnum value = gson.fromJson(resultingJson, TestEnum.class);
+    assertThat(value).isEqualTo(TestEnum.ONE);
+  }
+
+  @Test
+  public void enumValueCanBeParsed() {
+    TestData data = gson.fromJson("{\"value\":\"ONE\"}", TestData.class);
+    assertThat(data.value).isEqualTo(TestEnum.ONE);
+  }
+
+  @Test
+  public void mixedCaseEnumValueIsTreatedAsUnset() {
+    TestData data = gson.fromJson("{\"value\":\"oNe\"}", TestData.class);
+    assertThat(data.value).isNull();
+  }
+
+  @Test
+  public void lowerCaseEnumValueIsTreatedAsUnset() {
+    TestData data = gson.fromJson("{\"value\":\"one\"}", TestData.class);
+    assertThat(data.value).isNull();
+  }
+
+  @Test
+  public void notExistingEnumValueIsTreatedAsUnset() {
+    TestData data = gson.fromJson("{\"value\":\"FOUR\"}", TestData.class);
+    assertThat(data.value).isNull();
+  }
+
+  @Test
+  public void emptyEnumValueIsTreatedAsUnset() {
+    TestData data = gson.fromJson("{\"value\":\"\"}", TestData.class);
+    assertThat(data.value).isNull();
+  }
+
+  private static class TestData {
+    TestEnum value;
+
+    public TestData(TestEnum value) {
+      this.value = value;
+    }
+  }
+
+  private enum TestEnum {
+    ONE,
+    TWO
+  }
+}
diff --git a/plugins/plugin-manager b/plugins/plugin-manager
index f681e7e..833889d 160000
--- a/plugins/plugin-manager
+++ b/plugins/plugin-manager
@@ -1 +1 @@
-Subproject commit f681e7ecb6ddbc52fe9e07cf3672ccdcad7d7d0b
+Subproject commit 833889d327a159b5ccea7064f4fcff3f94d4b26e
diff --git a/plugins/webhooks b/plugins/webhooks
index 8078749..f860a0c 160000
--- a/plugins/webhooks
+++ b/plugins/webhooks
@@ -1 +1 @@
-Subproject commit 8078749bfd64d9dcd3372bc3f8965d192747c5b4
+Subproject commit f860a0cf6931164a6e5c2b333eaa0004ea14acec
diff --git a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.html b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.html
index e69d48f..1e50e4b 100644
--- a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.html
+++ b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.html
@@ -176,7 +176,7 @@
           on-cancel="_handleConfirmDialogCancel"
           branch="[[change.branch]]"
           has-parent="[[hasParent]]"
-          rebase-on-current="[[revisionActions.rebase.rebaseOnCurrent]]"
+          rebase-on-current="[[_revisionRebaseAction.rebaseOnCurrent]]"
           hidden></gr-confirm-rebase-dialog>
       <gr-confirm-cherrypick-dialog id="confirmCherrypick"
           class="confirmDialog"
@@ -216,7 +216,7 @@
           id="confirmSubmitDialog"
           class="confirmDialog"
           change="[[change]]"
-          action="[[revisionActions.submit]]"
+          action="[[_revisionSubmitAction]]"
           on-cancel="_handleConfirmDialogCancel"
           on-confirm="_handleSubmitConfirm" hidden></gr-confirm-submit-dialog>
       <gr-dialog id="createFollowUpDialog"
diff --git a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.js b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.js
index 83a454b..a448377 100644
--- a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.js
+++ b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.js
@@ -271,6 +271,20 @@
         type: Object,
         value() { return {}; },
       },
+      // If property binds directly to [[revisionActions.submit]] it is not
+      // updated when revisionActions doesn't contain submit action.
+      /** @type {?} */
+      _revisionSubmitAction: {
+        type: Object,
+        computed: '_getSubmitAction(revisionActions)',
+      },
+      // If property binds directly to [[revisionActions.rebase]] it is not
+      // updated when revisionActions doesn't contain rebase action.
+      /** @type {?} */
+      _revisionRebaseAction: {
+        type: Object,
+        computed: '_getRebaseAction(revisionActions)',
+      },
       privateByDefault: String,
 
       _loading: {
@@ -415,6 +429,28 @@
       this._handleLoadingComplete();
     },
 
+    _getSubmitAction(revisionActions) {
+      return this._getRevisionAction(revisionActions, 'submit', null);
+    },
+
+    _getRebaseAction(revisionActions) {
+      return this._getRevisionAction(revisionActions, 'rebase',
+        {rebaseOnCurrent: null}
+      );
+    },
+
+    _getRevisionAction(revisionActions, actionName, emptyActionValue) {
+      if (!revisionActions) {
+        return undefined;
+      }
+      if (revisionActions[actionName] === undefined) {
+        // Return null to fire an event when reveisionActions was loaded
+        // but doesn't contain actionName. undefined doesn't fire an event
+        return emptyActionValue;
+      }
+      return revisionActions[actionName];
+    },
+
     reload() {
       if (!this.changeNum || !this.latestPatchNum) {
         return Promise.resolve();
@@ -575,7 +611,9 @@
     _deleteAndNotify(actionName) {
       if (this.actions[actionName]) {
         delete this.actions[actionName];
-        this.notifyPath('actions.' + actionName);
+        // We assign a fake value of 'false' to support Polymer 2
+        // see https://github.com/Polymer/polymer/issues/2631
+        this.notifyPath('actions.' + actionName, false);
       }
     },
 
diff --git a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions_test.html b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions_test.html
index 184e175..b88e06b 100644
--- a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions_test.html
+++ b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions_test.html
@@ -1513,4 +1513,50 @@
       assert.equal(reportStub.lastCall.args[0], 'type-key');
     });
   });
+
+  suite('getChangeRevisionActions returns only some actions', () => {
+    let element;
+    let sandbox;
+    let changeRevisionActions;
+
+    setup(() => {
+      stub('gr-rest-api-interface', {
+        getChangeRevisionActions() {
+          return Promise.resolve(changeRevisionActions);
+        },
+        send(method, url, payload) {
+          return Promise.reject(new Error('error'));
+        },
+        getProjectConfig() { return Promise.resolve({}); },
+      });
+
+      sandbox = sinon.sandbox.create();
+      sandbox.stub(Gerrit, 'awaitPluginsLoaded').returns(Promise.resolve());
+
+      element = fixture('basic');
+      // getChangeRevisionActions is not called without
+      // set the following properies
+      element.change = {};
+      element.changeNum = '42';
+      element.latestPatchNum = '2';
+
+
+      sandbox.stub(element.$.confirmCherrypick.$.restAPI,
+          'getRepoBranches').returns(Promise.resolve([]));
+      sandbox.stub(element.$.confirmMove.$.restAPI,
+          'getRepoBranches').returns(Promise.resolve([]));
+      return element.reload();
+    });
+
+    teardown(() => {
+      sandbox.restore();
+    });
+
+    test('confirmSubmitDialog and confirmRebase properties are changed', () => {
+      changeRevisionActions = {};
+      element.reload();
+      assert.strictEqual(element.$.confirmSubmitDialog.action, null);
+      assert.strictEqual(element.$.confirmRebase.rebaseOnCurrent, null);
+    });
+  });
 </script>
diff --git a/polygerrit-ui/app/test/index.html b/polygerrit-ui/app/test/index.html
index 9448662..2b052a0 100644
--- a/polygerrit-ui/app/test/index.html
+++ b/polygerrit-ui/app/test/index.html
@@ -197,7 +197,6 @@
   for (let file of elements) {
     file = elementsPath + file;
     testFiles.push(file);
-    testFiles.push(file + '?dom=shadow');
   }
 
   // Behaviors tests.