docs: private String getPropertyLabel(PropertyIdValue propertyIdValue) {
  		PropertyRecord propertyRecord = this.propertyRecords
  				.get(propertyIdValue);
  		if (propertyRecord == null || propertyRecord.propertyDocument == null) {
  			return propertyIdValue.getId();
  		} else {
  			return getLabel(propertyIdValue, propertyRecord.propertyDocument);
  		}
  	}