docs: @Nullable
    @OverrideOnDemand
    protected ICommonsSet <String> onShowSelectedObjectCustomAttrs (@Nonnull final WPECTYPE aWPEC,
                                                                    @Nonnull final DATATYPE aSelectedObject,
                                                                    @Nonnull final Map <String, String> aCustomAttrs,
                                                                    @Nonnull final BootstrapViewForm aViewForm)
    {
      return null;
    }