MarkerDetailActivity must call onDestroy().

src/main/java/de/dennisguse/opentracks/ui/markers/MarkerDetailActivity.java

@@ -107,6 +107,13 @@ public class MarkerDetailActivity extends AbstractActivity implements DeleteMark
         return viewBinding.getRoot();
     }
 
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        viewBinding = null;
+        markerIds = null;
+    }
+
     @Override
     public void onMarkerDeleted() {
         runOnUiThread(this::finish);
@@ -129,7 +136,7 @@ public class MarkerDetailActivity extends AbstractActivity implements DeleteMark
             return markerIds.size();
         }
 
-        @Nullable //TODO Used?
+        @Nullable
         public CharSequence getPageTitle(int position) {
             return getString(R.string.marker_title, position + 1, getItemCount());
         }