src/Listener/Events/AjaxEvent.php
public function getContentType()
    {
        if (!$this->contentType) {
            $this->setContentType($this->getParam('contentType') ?: static::TYPE_JSON);
        }

        return $this->contentType;
    }
public function getContentType()
    {
        if (!$this->contentType) {
            $this->setContentType($this->getParam('contentType') ?: static::TYPE_JSON);
        }

        return $this->contentType;
    }
Get the content type.

@return string