How to use the terra-menu.ItemGroup function in terra-menu

isOpen={this.state.isOpen}
          targetRef={this.getButtonNode}
          contentWidth={contentWidth}
        >
          {this.wrapChildrenOnClick(children)}
        
        {clonedButton}
      
    );
  }
}

CollapsibleMenu.propTypes = propTypes;
CollapsibleMenu.childContextTypes = childContextTypes;
CollapsibleMenu.Item = Menu.Item;
CollapsibleMenu.ItemGroup = Menu.ItemGroup;
CollapsibleMenu.Opts = {
  widths: Menu.Opts.widths,
};

export default CollapsibleMenu;

{menuItems}
        
        <button>
          {!!accessory &amp;&amp; <div>{accessory}</div>}
          {!!title &amp;&amp; size !== 'tiny' &amp;&amp; <div>{title}</div>}
          {}
        </button>
      
    );
  }
}

Utility.propTypes = propTypes;
Utility.defaultProps = defaultProps;
Utility.Item = Menu.Item;
Utility.ItemGroup = Menu.ItemGroup;
Utility.Divider = Menu.Divider;
Utility.Opts = Menu.Opts;

export default Utility;

{...customProps}
          text="Utility Menu"
          onClick={this.handleOnClick}
          icon={buttonIcon}
          variant="utility"
        />
      
    );
  }
}

Utility.propTypes = propTypes;
Utility.defaultProps = defaultProps;

Utility.Item = Menu.Item;
Utility.ItemGroup = Menu.ItemGroup;
Utility.Divider = Menu.Divider;
Utility.Opts = Menu.Opts;

export default Utility;