add/assign catalogs to an api when adding it

src/Model/Entity/ExternalProductCatalogsProductCatalog.php

@@ -0,0 +1,40 @@
+<?php
+declare(strict_types=1);
+
+namespace CakeProducts\Model\Entity;
+
+use Cake\I18n\DateTime;
+use Cake\ORM\Entity;
+
+/**
+ * ExternalProductCatalogsProductCatalog Entity
+ *
+ * @property int $id
+ * @property string $external_product_catalog_id
+ * @property string $product_catalog_id
+ * @property DateTime $created
+ * @property bool $enabled
+ *
+ * @property ExternalProductCatalog $external_product_catalog
+ * @property ProductCatalog $product_catalog
+ */
+class ExternalProductCatalogsProductCatalog extends Entity
+{
+    /**
+     * Fields that can be mass assigned using newEntity() or patchEntity().
+     *
+     * Note that when '*' is set to true, this allows all unspecified fields to
+     * be mass assigned. For security purposes, it is advised to set '*' to false
+     * (or remove it), and explicitly make individual fields accessible as needed.
+     *
+     * @var array<string, bool>
+     */
+    protected array $_accessible = [
+        'external_product_catalog_id' => true,
+        'product_catalog_id' => true,
+        'created' => true,
+        'enabled' => true,
+        'external_product_catalog' => true,
+        'product_catalog' => true,
+    ];
+}