docs: protected Escalation findEscalationForEscalationEventDefinition(Element escalationEventDefinition) {
      String escalationRef = escalationEventDefinition.attribute("escalationRef");
      if (escalationRef == null) {
        addError("escalationEventDefinition does not have required attribute 'escalationRef'", escalationEventDefinition);
      } else if (!escalations.containsKey(escalationRef)) {
        addError("could not find escalation with id '" + escalationRef + "'", escalationEventDefinition);
      } else {
        return escalations.get(escalationRef);
      }
      return null;
    }