src/Widgets/Bootstrap/Card.php
protected function renderFooterImage() {
        if (!isset($this->footerImage)) {
            return '';
        }
        Html::addCssClass($this->footerImageOptions, ['widget' => 'card-img-bottom']);
        return $this->htmlHlp->img($this->footerImage, $this->footerImageOptions);
    }
protected function renderFooterImage() {
        if (!isset($this->footerImage)) {
            return '';
        }
        Html::addCssClass($this->footerImageOptions, ['widget' => 'card-img-bottom']);
        return $this->htmlHlp->img($this->footerImage, $this->footerImageOptions);
    }
Render card bottom image
@return string