@Nullable
  private static TransferableFileEditorState getEditorState(@NotNull FileEditor editor) {
    FileEditorState state = editor.getState(FileEditorStateLevel.FULL);
    return state instanceof TransferableFileEditorState ? (TransferableFileEditorState)state : null;
  }
@Nullable
  private static TransferableFileEditorState getEditorState(@NotNull FileEditor editor)