Missed nextPageToken check

CHANGELOG.md

@@ -1,5 +1,9 @@
 Change Log
 ---
+### 6.6.5 (2019-05-21)
+
+* Handle [breaking change](https://issuetracker.google.com/issues/133254108) in Google Tasks API
+
 ### 6.6.3 (2019-05-08)
 
 * Fix backup import crash

app/build.gradle

@@ -21,7 +21,7 @@ android {
     defaultConfig {
         testApplicationId "org.tasks.test"
         applicationId "org.tasks"
-        versionCode 580
+        versionCode 581
         versionName "6.6.4"
         targetSdkVersion 28
         minSdkVersion 16

app/src/main/java/org/tasks/gtasks/GoogleTaskSynchronizer.java

@@ -198,7 +198,7 @@ public class GoogleTaskSynchronizer {
         gtaskLists.addAll(items);
       }
       nextPageToken = remoteLists.getNextPageToken();
-    } while (nextPageToken != null);
+    } while (!Strings.isNullOrEmpty(nextPageToken));
     gtasksListService.updateLists(account, gtaskLists);
     Filter defaultRemoteList = defaultFilterProvider.getDefaultRemoteList();
     if (defaultRemoteList instanceof GtasksFilter) {