@Override
 public boolean process(IndexTree.Unit unit) {
   VirtualFile file = PersistentFS.getInstance().findFileById(unit.myFileId);
   if (file == null) {
     return true;
   }
   boolean process =
       isInSourceMode
           ? myProjectIndex.isInSourceContent(file)
           : myProjectIndex.isInLibraryClasses(file);
   if (process) {
     myHierarchyService.processUnit(unit);
     myProcessedSet.set(unit.myFileId);
   }
   return true;
 }