public Collection<VirtualFile> retainNewFiles(@NotNull String detectorId, @NotNull Collection<? extends VirtualFile> files) {
    synchronized (myLock) {
      IntSet existentFilesSet = null;
      try {
        existentFilesSet = myExistentFrameworkFiles.get(detectorId);
      }
      catch (IOException e) {
        LOG.info(e);
      }

      List<VirtualFile> newFiles = new ArrayList<>();
      for (VirtualFile file : files) {
        final int fileId = FileBasedIndex.getFileId(file);
        if (existentFilesSet == null || !existentFilesSet.contains(fileId)) {
          newFiles.add(file);
        }
      }
      return newFiles;
    }
  }
public Collection<VirtualFile> retainNewFiles(@NotNull String detectorId, @NotNull Collection<? extends VirtualFile> files)