bel="Button group with nested dropdown">
            <button type="button" class="btn btn-primary">Primary</button>
            <div class="btn-group" role="group">
              <button id="btnGroupDrop1" type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"></button>
              <div class="dropdown-menu" aria-labelledby="btnGroupDrop1">
                <a class="dropdown-item" href="#">Dropdown link</a>
                <a class="dropdown