/**
   * Ensures that the operation being executed is a GetFeature operation.
   *
   * <p>Subclasses may implement
   */
  public boolean canHandle(Operation operation) {
    // GetFeature operation?
    if ("GetFeature".equalsIgnoreCase(operation.getId())
        || "GetFeatureWithLock".equalsIgnoreCase(operation.getId())) {
      // also check that the resultType is "results"
      GetFeatureRequest req = GetFeatureRequest.adapt(operation.getParameters()[0]);
      if (req.isResultTypeResults()) {
        // call subclass hook
        return canHandleInternal(operation);
      }
    }

    return false;
  }
  public ValueCollectionType run(GetPropertyValueType request) throws WFSException {
    // check the request resolve
    if (request.isSetResolve() && !ResolveValueType.NONE.equals(request.getResolve())) {
      throw new WFSException(request, "Only resolve = none is supported", "InvalidParameterValue")
          .locator("resolve");
    }

    if (request.getValueReference() == null) {
      throw new WFSException(request, "No valueReference specified", "MissingParameterValue")
          .locator("valueReference");
    }

    // do a getFeature request
    GetFeatureType getFeature = Wfs20Factory.eINSTANCE.createGetFeatureType();
    getFeature.getAbstractQueryExpression().add(request.getAbstractQueryExpression());

    FeatureCollectionType fc =
        (FeatureCollectionType) delegate.run(GetFeatureRequest.adapt(getFeature)).getAdaptee();

    QueryType query = (QueryType) request.getAbstractQueryExpression();
    QName typeName = (QName) query.getTypeNames().iterator().next();
    FeatureTypeInfo featureType =
        catalog.getFeatureTypeByName(typeName.getNamespaceURI(), typeName.getLocalPart());

    try {
      // look for the attribute type
      AttributeTypeInfo attribute = null;
      for (AttributeTypeInfo at : featureType.attributes()) {
        if (at.getName().equals(request.getValueReference())) {
          attribute = at;
          break;
        }
      }
      if (attribute == null) {
        throw new WFSException(request, "No such attribute: " + request.getValueReference());
      }

      AttributeDescriptor descriptor = attribute.getAttribute();
      if (descriptor == null) {
        PropertyDescriptor pd = featureType.getFeatureType().getDescriptor(attribute.getName());
        if (pd instanceof AttributeDescriptor) {
          descriptor = (AttributeDescriptor) pd;
        }
      }

      if (descriptor == null) {
        throw new WFSException(request, "Unable to obtain descriptor for " + attribute.getName());
      }

      // create value collection type from feature collection
      ValueCollectionType vc = Wfs20Factory.eINSTANCE.createValueCollectionType();
      vc.setTimeStamp(fc.getTimeStamp());
      vc.setNumberMatched(fc.getNumberMatched());
      vc.setNumberReturned(fc.getNumberReturned());
      vc.getMember().add(new PropertyValueCollection(fc.getMember().iterator().next(), descriptor));
      // TODO: next/previous but point back at GetPropertyValue
      // vc.setNext(fc.getNext());
      // vc.setPrevious(fc.getPrevious());
      return vc;
    } catch (IOException e) {
      throw new WFSException(request, e);
    }
  }