问Angular UI Bootstrap Popover -如何添加关闭按钮

EN

<td ng-repeat="i in c.installments" ng-class="{ 'first' : i.first, 'last' : i.last, 'advance' : i.advance.value > 0, 'edited' : i.edited, 'final-installment' : i.last }" popover-trigger="{{ popoverFilter(i) }}" popover-placement="top" popover-title="{{i.id == 0 ? 'Advance' : 'Installment ' + i.id}}" popover-append-to-body="true" popover-template="popoverTemplate(i)" ng-init="payment= i; newpayment= i.amount.rounded_value" >

<script type="text/ng-template" id="editPopoverTemplate.html">
    <form name="editPayment">
      <h2>{{payment.amount.value|currency:undefined:cents}}</h2>
      <div class="form-group" ng-class="{ 'has-error' : editPayment.newpayment.$invalid }">
        <label>New value:</label>
        <input type="number" name="newpayment" ng-model="newpayment" class="form-control no-spinner" step="1" min="10" required>
        <span ng-messages="editPayment.newpayment.$error" class="help-block" role="alert">
          <span ng-message="required">The value is mandatory</span>
          <span ng-message="min">The value is too low</span>
          <span ng-message="max">The value is too hight</span>
        </span>
      </div>
      <div class="btn-group btn-group-justified" role="group">
        <div class="btn-group" role="group">
          <button class="btn" type="button">Cancel</button>
        </div>
        <div class="btn-group" role="group">
          <button class="btn btn-primary" type="button" ng-disabled="editPayment.$invalid">Save</button>
        </div>
      </div>
    </form>
  </script>