Cleanup.

src/main/java/de/dennisguse/opentracks/data/TrackDataHub.java

@@ -416,8 +416,7 @@ public class TrackDataHub {
          *
          * @param track the track
          */
-        //TODO Could be @NonNull
-        void onTrackUpdated(Track track);
+        void onTrackUpdated(@NonNull Track track);
 
         /**
          * Called to clear previously-sent track points.

src/main/java/de/dennisguse/opentracks/data/models/Speed.java

@@ -38,15 +38,6 @@ public record Speed(double speed_mps) {
         return speed2;
     }
 
-    public static Speed absDiff(Speed speed1, Speed speed2) {
-        //TODO Why Math.abs? Seems to be a leftover.
-        return Speed.of(Math.abs(speed1.speed_mps - speed2.speed_mps));
-    }
-
-    public Speed mul(double factor) {
-        return new Speed(factor * speed_mps);
-    }
-
     public boolean isZero() {
         return speed_mps == 0;
     }

src/main/java/de/dennisguse/opentracks/io/file/importer/ImportViewModel.java

@@ -49,7 +49,6 @@ public class ImportViewModel extends AndroidViewModel implements ImportServiceRe
     private void loadData(List<DocumentFile> documentFiles) {
         List<ArrayList<DocumentFile>> nestedFileList = documentFiles.stream()
                 .map(FileUtils::getFiles)
-                // TODO flatMap(Collection::stream) fails with ClassCastException; try in the future again
                 .collect(Collectors.toList());
 
         List<DocumentFile> fileList = new ArrayList<>();

src/main/java/de/dennisguse/opentracks/ui/util/ListItemUtils.java

@@ -75,7 +75,6 @@ public class ListItemUtils {
             // Match list_item_time_distance in list_item.xml
 
             String time = StringUtils.formatElapsedTime(totalTime);
-            // TODO unit system
             String distance = DistanceFormatter.Builder()
                     .setUnit(unitSystem)
                     .build(context)