Adapt message requests to support invite flow.

app/src/main/java/org/thoughtcrime/securesms/sms/MessageSender.java

@@ -83,6 +83,9 @@ public class MessageSender {
 
   private static final String TAG = MessageSender.class.getSimpleName();
 
+  /**
+   * Suitable for a 1:1 conversation or a GV1 group only.
+   */
   @WorkerThread
   public static void sendProfileKey(final Context context, final long threadId) {
     ApplicationDependencies.getJobManager().add(ProfileKeySendJob.create(context, threadId));