@Override
    public void markInitialState()
    {
        if (isRowStatePreserved())
        {
            if (getFacesContext().getAttributes().containsKey(StateManager.IS_BUILDING_INITIAL_STATE))
            {
                _initialDescendantFullComponentState = saveDescendantInitialComponentStates(getFacesContext(), getChildren().iterator(), false);
            }
        }
        super.markInitialState();
    }
<p class="changed_added_2_1">Override the base class method to
take special action if the method is being invoked when {@link
StateManager#IS_BUILDING_INITIAL_STATE} is true
<strong>and</strong> the <code>rowStatePreserved</code>
JavaBeans property for this instance is <code>true</code>.</p>

<p class="changed_modified_2_1">The additional action taken is to
traverse the descendents and save their state without regard to
any particular row value.</p>

@since 2.1
primefaces/src/main/java/org/primefaces/component/patch/UIDataPatch.java