ISSUE-11477 - fixed Swagger response for searchCriteria - added zero index to array signifier

Author: Jakub Idziak

app/code/Magento/Webapi/Model/Rest/Swagger/Generator.php

@@ -39,7 +39,7 @@ class Generator extends AbstractSchemaGenerator
     const UNAUTHORIZED_DESCRIPTION = '401 Unauthorized';
 
     /** Array signifier */
-    const ARRAY_SIGNIFIER = '[]';
+    const ARRAY_SIGNIFIER = '[0]';
 
     /**
      * Swagger factory instance.