public void save(final Map options) throws IOException {
                // this is the structure I'm trying to build (including multiplcities)
                // indentations indicate containment.
		// DocumentRoot [1]
		// - Container : AnyType [1]
		// -- Annotation : AnyType [0..*]
		// --- TargetID : String [1]
		// --- Entry : AnyType [0..*]
		// ---- Key : String [1]
		// ---- Value : String [1]
		options.put(XMLResource.OPTION_RECORD_UNKNOWN_FEATURE, Boolean.TRUE);
		ExtendedMetaData extendedMetaData = new BasicExtendedMetaData(this.getResourceSet().getPackageRegistry());
		options.put(XMLResource.OPTION_EXTENDED_META_DATA, extendedMetaData);
		// add the required properties
		EStructuralFeature rootFeature = extendedMetaData.demandFeature(null, "root", true);
		EClass rootClass = rootFeature.getEContainingClass();
		EObject documentRoot = EcoreUtil.create(rootClass);
		EMap xmlnsPrefixMap = (EMap) documentRoot.eGet(extendedMetaData.getXMLNSPrefixMapFeature(rootClass));
		xmlnsPrefixMap.put(this.NAMESPACE_PREFIX, this.NAMESPACE_URI);
		AnyType container = XMLTypeFactory.eINSTANCE.createAnyType();
		documentRoot.eSet(rootFeature, container);
		EStructuralFeature entryFeature = extendedMetaData.demandFeature(this.NAMESPACE_URI, "entry", true);
		EStructuralFeature targetIDFeature = extendedMetaData.demandFeature(this.NAMESPACE_URI, "targetID", false);
		EStructuralFeature propretyValueFeature = extendedMetaData.demandFeature(this.NAMESPACE_URI, "propertyValue",
				false);
		EStructuralFeature propertyNameFeature = extendedMetaData.demandFeature(this.NAMESPACE_URI, "propertyName",
				false);
		EStructuralFeature annotationsFeature = extendedMetaData.demandFeature(this.NAMESPACE_URI, "annotations", true);
		for (Entry<EObject, Map<String, String>> entry : this.unknownFeatureMap.entrySet()) {
			EObject eObject = entry.getKey();
			Set<Entry<String, String>> propertyValueSet = entry.getValue().entrySet();
			AnyType annotation = XMLTypeFactory.eINSTANCE.createAnyType();
			String eObjectID = this.getID(eObject);
			annotation.getMixed().add(targetIDFeature, eObjectID);
			for (Entry<String, String> propertyValuePair : propertyValueSet) {
				String propertyName = propertyValuePair.getKey();
				String propertyValue = propertyValuePair.getValue();
				AnyType mapEntry = XMLTypeFactory.eINSTANCE.createAnyType();
				mapEntry.getMixed().set(propertyNameFeature, propertyName);
				mapEntry.getMixed().set(propretyValueFeature, propertyValue);
				annotation.getMixed().add(entryFeature, mapEntry);
			}
			container.getMixed().add(annotationsFeature, annotation);
		}
		this.getContents().add(documentRoot);
		super.save(options);
	}