/**
  * @param \Magento\Framework\DataObject $agreementData
  * @return array|bool
  */
 public function validateData($agreementData)
 {
     $errors = [];
     $contentHeight = $agreementData->getContentHeight();
     if ($contentHeight !== '' && !preg_match('/^[0-9]*\\.*[0-9]+(' . implode("|", $this->allowedCssUnits) . ')?$/', $contentHeight)) {
         $errors[] = "Please input a valid CSS-height. For example 100px or 77pt or 20em or .5ex or 50%.";
     }
     return count($errors) ? $errors : true;
 }