🚧 Add complex types from docs

src/Entity/Item/Category.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Shikiryu\SRSS\Entity\Item;
+
+use Shikiryu\SRSS\Entity\SRSSElement;
+use Shikiryu\SRSS\Validator\HasValidator;
+use Shikiryu\SRSS\Validator\Validator;
+
+class Category extends HasValidator implements SRSSElement
+{
+    /**
+     * @string
+     */
+    public string $domain;
+    /**
+     * @string
+     */
+    public string $value;
+
+    public function isValid(): bool
+    {
+        try {
+            return (new Validator())->isObjectValid($this);
+        } catch (\ReflectionException $e) {
+            return false;
+        }
+    }
+
+    public function toArray(): array
+    {
+        return get_object_vars($this);
+    }
+}