magento2 – Magento 2 Async WebAPI: Data in topic must be of type mixed. array given

I’m using magento v2.3.4 and created a Magento 2 rest webapi function like this:

 * POST for create brands api
 * @param mixed $data
 * @return array
public function create($data);

I usually use the API using this URL:


with data like this:

    "data": (
            "name": "Adidas",
            "type": "apparel"
            "name": "Nike",
            "type": "apparel"

The problem arise when I tried to use the async function in the REST Webapi url:


Then I got the following error:

“error_message”: “Data in topic “” must be of type “mixed”. “array” given.”