deserialize method

Implementation

@override
void deserialize(XmlElement xml) {
  // deserialize
  super.deserialize(xml);

  // set properties
  alarming =
      Xml.get(node: xml, tag: 'alarm') ?? Xml.get(node: xml, tag: 'error') ?? Xml.get(node: xml, tag: 'value');
  text =
      Xml.get(node: xml, tag: 'text') ?? Xml.get(node: xml, tag: 'errortext');
  onalarm = Xml.get(node: xml, tag: 'onalarm');
}