Personalizar campos del checkout con LayoutProcessor en Magento 2

<type name="Magento\Checkout\Block\Checkout\LayoutProcessor">
    <plugin name="gdw_checkout_layout_plugin" type="GDW\Hello\Plugin\CheckoutLayout"/>
</type>

<?php
namespace GDW\Hello\Plugin;

class CheckoutLayout
{
    public function afterProcess($subject, array $jsLayout): array
    {
        $path = & $jsLayout['components']['checkout']['children']['steps']['children']
            ['shipping-step']['children']['shippingAddress']['children']
            ['shipping-address-fieldset']['children'];

        $path['gdw_reference'] = [
            'component' => 'Magento_Ui/js/form/element/abstract',
            'config' => ['customScope' => 'shippingAddress.custom_attributes'],
            'dataScope' => 'shippingAddress.custom_attributes.gdw_reference',
            'label' => 'Referencia de entrega',
            'provider' => 'checkoutProvider',
            'visible' => true,
            'validation' => ['required-entry' => false],
            'sortOrder' => 250,
        ];

        return $jsLayout;
    }
}