Remove usage of deprecated Notification.setListener(..) (#8317)

Also: cleanup of nullability parameters in `FlutterMessages.java`

Author: jwren

flutter-idea/src/io/flutter/FlutterMessages.java

@@ -6,7 +6,6 @@
 package io.flutter;
 
 import com.intellij.notification.Notification;
-import com.intellij.notification.NotificationListener;
 import com.intellij.notification.NotificationType;
 import com.intellij.notification.Notifications;
 import com.intellij.openapi.project.Project;
@@ -23,24 +22,24 @@ public class FlutterMessages {
   private FlutterMessages() {
   }
 
-  public static void showError(String title, @NotNull String message, @Nullable Project project) {
+  public static void showError(@NotNull String title, @NotNull String message, @Nullable Project project) {
     Notifications.Bus.notify(
       new Notification(FLUTTER_NOTIFICATION_GROUP_ID,
                        title,
                        message,
                        NotificationType.ERROR), project);
   }
 
-  public static void showWarning(String title, String message, @Nullable Project project) {
+  public static void showWarning(@NotNull String title, @NotNull String message, @Nullable Project project) {
     Notifications.Bus.notify(
       new Notification(
         FLUTTER_NOTIFICATION_GROUP_ID,
         title,
         message,
-        NotificationType.WARNING).setListener(NotificationListener.URL_OPENING_LISTENER), project);
+        NotificationType.WARNING), project);
   }
 
-  public static void showInfo(String title, String message, @Nullable Project project) {
+  public static void showInfo(@NotNull String title, @NotNull String message, @Nullable Project project) {
     final Notification notification = new Notification(
       FLUTTER_NOTIFICATION_GROUP_ID,
       title,

flutter-idea/src/io/flutter/run/daemon/DeviceDaemon.java

@@ -18,6 +18,7 @@
 import com.intellij.openapi.ui.Messages;
 import com.intellij.openapi.util.SystemInfo;
 import com.intellij.openapi.util.io.FileUtil;
+import com.intellij.openapi.util.text.StringUtil;
 import io.flutter.FlutterMessages;
 import io.flutter.FlutterUtils;
 import io.flutter.android.IntelliJAndroidSdk;
@@ -361,14 +362,16 @@ public void onDaemonLogMessage(@NotNull DaemonEvent.DaemonLogMessage message) {
 
     @Override
     public void onDaemonShowMessage(@NotNull DaemonEvent.DaemonShowMessage event) {
-      if ("error".equals(event.level)) {
-        FlutterMessages.showError(event.title, event.message, null);
-      }
-      else if ("warning".equals(event.level)) {
-        FlutterMessages.showWarning(event.title, event.message, null);
-      }
-      else {
-        FlutterMessages.showInfo(event.title, event.message, null);
+      if (StringUtil.isNotEmpty(event.level) && StringUtil.isNotEmpty(event.title) && StringUtil.isNotEmpty(event.message)) {
+        if ("error".equals(event.level)) {
+          FlutterMessages.showError(event.title, event.message, null);
+        }
+        else if ("warning".equals(event.level)) {
+          FlutterMessages.showWarning(event.title, event.message, null);
+        }
+        else {
+          FlutterMessages.showInfo(event.title, event.message, null);
+        }
       }
     }