code: public function render(ElementInterface $element)
      {
          $renderer = $this->getView();
  
          if (!method_exists($renderer, 'plugin')) {
              return '';
          }
  
          $wrapperClass     = '';
          $elementMarkup    = '';
          $templateMarkup   = '';
          $attributesString = '';
          $label            = '';
  
          if ($element instanceof CollectionElement && $element->shouldCreateTemplate()) {
              $templateMarkup = $this->renderTemplate($element);
          }
  
          foreach ($element->getIterator() as $elementOrFieldset) {
              /** @var  ElementInterface $elementOrFieldset */
              $elementMarkup .= $this->renderElement($elementOrFieldset);
          }
  
          $helperFormButtonIcon = $this->getFormButtonIconHelper();
          $helperLabel          = $this->getLabelHelper();
  
          $elementMarkup .= sprintf(
              $this->elementWrap,
              '',
              $helperFormButtonIcon(
                  new Button(
                      null,
                      [
                          'label' => 'Add New',
                          'icon'  => 'fa fa-plus-circle'
                      ]
                  )
              ),
              ''
          );
  
          if ($this->shouldWrap) {
              $attributes = $element->getAttributes();
  
              /** @noinspection UnSafeIsSetOverArrayInspection */
              if (isset($attributes['class'])) {
                  $wrapperClass = $attributes['class'];
  
                  unset($attributes['class']);
              }
  
              unset($attributes['name']);
  
              $attributesString = count($attributes) ? ' ' . $this->createAttributesString($attributes) : '';
  
              /** @noinspection IsEmptyFunctionUsageInspection */
              if (!empty($element->getLabel())) {
                  $label = $helperLabel($element);
              }
          }
  
          return sprintf(
              $this->wrapper,
              $wrapperClass,
              $attributesString,
              $label,
              $this->horizontalWrapClass,
              $elementMarkup,
              $templateMarkup
          );
      }
docs: Render a collection by iterating through all fieldset and elements.
  
  @param ElementInterface $element
  
  @return string
  @throws \RuntimeException
  @throws \Zend\Form\Exception\InvalidArgumentException