void (final @NotNull GroupItem group, final @NotNull ComponentItem item) { // class -> item final String componentClassName = item.getClassName(); if (getItem(componentClassName) != null) { Messages.showMessageDialog( UIDesignerBundle.message("error.item.already.added", componentClassName), ApplicationNamesInfo.getInstance().getFullProductName(), Messages.getErrorIcon() ); return; } myClassName2Item.put(componentClassName, item); // group -> items group.addItem(item); // Process special predefined item for JPanel if ("javax.swing.JPanel".equals(item.getClassName())) { myPanelItem = item; } }