code: function fromXML($xmlElement)
      {
          $this->contact = new ReportContact();
          $this->contact->fromXML($xmlElement->contact);
  
          if (isset($xmlElement->mailing_id)) $this->mailingId = $xmlElement->mailing_id;
          if (isset($xmlElement->source)) $this->source = $xmlElement->source;
          if (isset($xmlElement->timestamp)) $this->timestamp = $xmlElement->timestamp;
      }
docs: Initializes this unsubscription from an XML representation.
  
  @param SimpleXMLElement $xmlElement
  the XML representation to use