@Nullable
  private static DiffViewerBase getViewer(@NotNull AnActionEvent e) {
    DiffViewerBase diffViewer = ObjectUtils.tryCast(e.getData(DiffDataKeys.DIFF_VIEWER), DiffViewerBase.class);
    if (diffViewer != null) return diffViewer;

    TextMergeViewer mergeViewer = ObjectUtils.tryCast(e.getData(DiffDataKeys.MERGE_VIEWER), TextMergeViewer.class);
    if (mergeViewer != null) return mergeViewer.getViewer();

    return null;
  }
@Nullable
  private static DiffViewerBase getViewer(@NotNull AnActionEvent e)