IModel instance = engine.getTemplateInstance();
Resource instanceResource = instance.getModelResource();
EObject javaRoot = instanceResource.getContents().get(0);
EObject javaClass = javaRoot.eContents().get(0);
EStructuralFeature memberFeature = javaClass.eClass().getEStructuralFeature("members");
List<EObject> classMembers = (List<EObject>)javaClass.eGet(memberFeature);
assert(Util.getElementName(classMembers.get(1)).matches("p1"));
EObject fieldP1 = classMembers.get(1);
EObject fieldP4 = EObjectCopier.copyElement(fieldP1, fieldP1.eClass().getEPackage());
fieldP4.eSet(fieldP4.eClass().getEStructuralFeature("name"),"p4");