@NotNull
  @Override
  public String getTitle(@Nullable VirtualFile file1, @Nullable VirtualFile file2) {
    FilePath path1 = file1 != null ? new LocalFilePath(file1.getPath(), file1.isDirectory()) : null;
    FilePath path2 = file2 != null ? new LocalFilePath(file2.getPath(), file2.isDirectory()) : null;
    return getTitle(path1, path2, DIFF_TITLE_SEPARATOR);
  }
@NotNull
  @Override
  public String getTitle(@Nullable VirtualFile file1, @Nullable VirtualFile file2)