fix examples

packages/dart_client/example/android/gradle.properties

@@ -1,3 +1,4 @@
 org.gradle.jvmargs=-Xmx1536M
 android.useAndroidX=true
 android.enableJetifier=true
+android.enableR8=true

packages/dart_client/example/android/gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.5-bin.zip

packages/dart_client/example/lib/main.dart

@@ -156,7 +156,7 @@ class _MessageViewState extends State<MessageView> {
   /// Convenience method for scrolling the list view when a new message is sent.
   void _updateList() {
     _scrollController.animateTo(
-      _scrollController.position.maxScrollExtent,
+      0,
       duration: const Duration(milliseconds: 200),
       curve: Curves.easeOut,
     );