@Override
        public VisitResult visit(VisitContext context, UIComponent target) {
            if (target instanceof EditableValueHolder) {
                callback.invokeContextCallback(context.getFacesContext(), target);
                return VisitResult.COMPLETE;
            }
            else if (UIComponent.isCompositeComponent(target)) {
                return visitEditableValueHolderTargets(context, target);
            }
            return VisitResult.ACCEPT;
        }
Invoke callback on the first rendered {@link EditableValueHolder} component
primefaces/src/main/java/org/primefaces/util/CompositeUtils.java