void () { registerDomExtender(MyCustomChildrenElement.class, CustomDomExtender.class); MyCustomChildrenElement myElement = createElement("<a><xx/><yy/><concrete-child/><some-concrete-child/></a>", MyCustomChildrenElement.class); DomCollectionChildDescription description = myElement.getGenericInfo().getCollectionChildDescription("xx"); assertThat(description).isNotNull(); assertInstanceOf(assertOneElement(description.getValues(myElement)), MyDynamicElement.class); assertInstanceOf(assertOneElement(myElement.getCustomChidren()), MyCustomElement.class); assertInstanceOf(assertOneElement(myElement.getConcreteChildren()), MyConcreteElement.class); assertNotNull(assertInstanceOf(myElement.getSomeConcreteChild(), MyConcreteElement.class).getXmlTag()); }