feature: add a JsonContent attributes

fill the content property of the request body

src/OpenApi/Attributes/JsonContent.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KnpLabs\JsonSchemaBundle\OpenApi\Attributes;
+
+use KnpLabs\JsonSchema\JsonSchemaInterface;
+use OpenApi\Attributes\JsonContent as AttributesJsonContent;
+
+class JsonContent extends AttributesJsonContent
+{
+    /**
+     * @param class-string $schema
+     */
+    public function __construct(string $schemaClass)
+    {
+        /**
+         * @var JsonSchemaInterface
+         */
+        $schema = new $schemaClass();
+
+        parent::__construct(
+                schema: json_encode($schema->jsonSerialize()),
+                example: iterator_to_array($schema->getExamples()),
+                title: $schema->getTitle(),
+                description: $schema->getDescription(),
+        );
+    }
+}