Not able to display checkbox in multiple select dropdown

I have a select dropdown with multiselect checkbox option

Initial View

After selecting value

Selection of value is working fine, but in the first image the checkbox are not visible

I have used bootstrap select multiple select box functionality.

code:

<select class="form-control fruits selectpicker" multiple  id="fruits" name="fruits" title="fruits">
    <option value="">apple </option>
    <option value="banana">banana</option>
    <option value="orange">orange</option>
    <option value="grapes">grapes</option>
  </select>

I want that in the first image the checkbox should be visible, can anyone tell me how to display it