Skip importing channels without group

app/src/main/java/eu/faircode/email/ApplicationEx.java

@@ -35,6 +35,7 @@ import android.os.Build;
 import android.os.DeadSystemException;
 import android.os.Handler;
 import android.os.RemoteException;
+import android.text.TextUtils;
 import android.view.OrientationEventListener;
 import android.webkit.CookieManager;
 
@@ -375,6 +376,12 @@ public class ApplicationEx extends Application {
         for (int c = 0; c < jchannels.length(); c++) {
             JSONObject jchannel = (JSONObject) jchannels.get(c);
 
+            // Legacy
+            if (!jchannel.has("group") ||
+                    jchannel.isNull("group") ||
+                    TextUtils.isEmpty(jchannel.getString("group")))
+                continue;
+
             String id = jchannel.getString("id");
             if (nm.getNotificationChannel(id) == null) {
                 NotificationChannel channel = new NotificationChannel(
@@ -382,12 +389,10 @@ public class ApplicationEx extends Application {
                         jchannel.getString("name"),
                         jchannel.getInt("importance"));
 
-                if (jchannel.has("group") && !jchannel.isNull("group")) {
                 String groupName = jchannel.getString("group");
                 NotificationChannelGroup group = new NotificationChannelGroup(groupName, groupName);
                 nm.createNotificationChannelGroup(group);
                 channel.setGroup(groupName);
-                }
 
                 if (jchannel.has("description") && !jchannel.isNull("description"))
                     channel.setDescription(jchannel.getString("description"));
@@ -407,7 +412,6 @@ public class ApplicationEx extends Application {
                 channel.enableVibration(jchannel.getBoolean("vibrate"));
 
                 Log.i("Creating channel=" + channel);
-                nm.deleteNotificationChannel(id);
                 nm.createNotificationChannel(channel);
             }
         }