Method getInput

/**
 * Method to get the content history field input markup.
 *
 * @return  string  The field input markup.
 *
 * @since   3.2
 */
protected function getInput()
{
    if (empty($this->layout)) {
        throw new \UnexpectedValueException(sprintf('%s has no layout assigned.', $this->name));
    }
    return $this->getRenderer($this->layout)->render($this->getLayoutData());
}