private static void addChild(final Object container, final Element element) { if (container instanceof ImmutableContainer.Builder) { ((ImmutableContainer.Builder) container).addChilds(element); return; } else if (container instanceof ImmutableContainerForMulti.Builder) { ((ImmutableContainerForMulti.Builder) container).addChilds(element); return; } ((Container) container).getChilds().add(element); }