For Medium article "Symfony EasyAdmin: complex forms" - example of non working config

purchase.yml

easy_admin:
    entities:
        Purchase:
            class: App\Entity\Purchase
            controller: App\Controller\Admin\PurchaseController
            disabled_actions: ['delete']
            list:
                actions: [ { name: 'show', icon: 'shopping-basket' } ]
                fields: ['guid', 'buyer', 'deliveryDate', 'deliveryHour', 'billingAddress', 'purchasedItems', 'total']
            form:
                fields:
                    - { type: 'group', label: 'Delivery Details', icon: 'truck', css_class: 'col-sm-4' }
                    - deliveryDate
                    - deliveryHour
                    - { type: 'divider' }
                    - { property: 'billingAddress.line1', label: 'Address line one' }
                    - { property: 'billingAddress.line2', label: 'Address line two' }
                    - { property: 'billingAddress.postCode', label: 'Post code' }
                    - { property: 'billingAddress.city', label: 'City' }
                    - { property: 'billingAddress.country', label: 'Country' }
                    - { type: 'group', label: 'Purchase Details', icon: 'shopping-cart', css_class: 'col-sm-4' }
                    - { property: 'guid', type_options: { 'disabled': true } }
                    - { property: 'buyer', type: 'easyadmin_autocomplete' }