AnchorView refDefault = ref != null ? views.getDefaultAnchor(ref) : null;
Preconditions.checkArgument(ref == null || refDefault != null, "ref is not rendered");
// Render thread in default anchor (and move to inline if there is one).
AnchorView defaultUi = blipUi.insertDefaultAnchorAfter(refDefault, thread);
InlineThreadView threadUi = defaultUi.getThread();
AnchorView inlineUi = views.getInlineAnchor(thread);
if (inlineUi != null) {
defaultUi.detach(threadUi);
inlineUi.attach(threadUi);
}