public Collection<FileIndexingRequest> scan(@NotNull ProjectDumbIndexingHistoryImpl projectDumbIndexingHistory) {
    long refreshedFilesCalcDuration = System.nanoTime();
    Collection<FileIndexingRequest> files = Collections.emptyList();
    try {
      FileBasedIndexImpl fileBasedIndex = (FileBasedIndexImpl)FileBasedIndex.getInstance();
      files = fileBasedIndex.getFilesToUpdate(myProject);
      return files;
    }
    finally {
      refreshedFilesCalcDuration = System.nanoTime() - refreshedFilesCalcDuration;
      projectDumbIndexingHistory.setChangedFilesDuringIndexingStatistics(
        new ChangedFilesDuringIndexingStatistics(files.size(), refreshedFilesCalcDuration));

      LOG.info("Retrieving changed during indexing files of " + myProject.getName() + " : " + files.size() + " to update, " +
               "calculated in " + TimeUnit.NANOSECONDS.toMillis(refreshedFilesCalcDuration) + "ms");
    }
  }
public Collection<FileIndexingRequest> scan(@NotNull ProjectDumbIndexingHistoryImpl projectDumbIndexingHistory)