use model class for request body with additionalProperties (#16613)

* try out simple fix

* add test case

* generate samples

samples/server/petstore/php-laravel/lib/app/Http/Controllers/FakeController.php

@@ -397,6 +397,30 @@ class FakeController extends Controller
 
         return response('How about implementing testInlineAdditionalProperties as a post method ?');
     }
+    /**
+     * Operation testInlineFreeformAdditionalProperties
+     *
+     * test inline free-form additionalProperties.
+     *
+     *
+     * @return Http response
+     */
+    public function testInlineFreeformAdditionalProperties()
+    {
+        $input = Request::all();
+
+        //path params validation
+
+
+        //not path params validation
+        if (!isset($input['testInlineFreeformAdditionalPropertiesRequest'])) {
+            throw new \InvalidArgumentException('Missing the required parameter $testInlineFreeformAdditionalPropertiesRequest when calling testInlineFreeformAdditionalProperties');
+        }
+        $testInlineFreeformAdditionalPropertiesRequest = $input['testInlineFreeformAdditionalPropertiesRequest'];
+
+
+        return response('How about implementing testInlineFreeformAdditionalProperties as a post method ?');
+    }
     /**
      * Operation testJsonFormData
      *

samples/server/petstore/php-laravel/lib/app/Models/TestInlineFreeformAdditionalPropertiesRequest.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * TestInlineFreeformAdditionalPropertiesRequest
+ */
+namespace app\Models;
+
+/**
+ * TestInlineFreeformAdditionalPropertiesRequest
+ */
+class TestInlineFreeformAdditionalPropertiesRequest {
+
+    /** @var string $someProperty */
+    public $someProperty = "";
+
+}