Field required validation error getting after sending data also

I am getting error

 "message": {
        "business.name": [
            "The business.name field is required."
        ]
    },

I am sending business.name in body, but still getting error. Why?

This is my body

{
  
  "business": {
    "name": "Hello",
    "gst": "07ARVPJ6970C1ZE"
  },
  "firstName": "Ashish",
  "address": {
    "cityId": "707"
  }
}

my controller

public function register(Request $request)
    {

        $this->customRequest = SellerCreateRequest::class;
        $this->jobMethod = 'sellerRegister';        
        return $this->handleCustomEndPoint(SellerCreateJob::class, $request);
    }

my validation request file

public function rules()
    {
        return [
            
            'business.name' => [
                'required',
                'string'
            ],
           
        ];
    }

via Chebli Mohamed