I am new to Refit Library and having an issue filtering data using UserDefinedFields.

below is an example data;

{
  "items": [
    {
      "id": 0,
      "companyName": "AmeriGas Cons",
      "isDefault": true,
      "lastActivityDate": "2023-08-07T02:52:57.12Z",
      "ResourceID": 29682886,
      "userDefinedFields": [
        {
          "name": "Cons Elec",
          "value": null
        },
        {
          "name": "Partner GID",
          "value": null
        }
      ]
    },
    {
      "id": 174,
      "companyName": "Janssen CoaocoStar,Inc.",
      "isDefault": true,
      "lastActivityDate": "2024-07-11T16:52:15.95Z",
      "ResourceID": 29682886,
      "userDefinedFields": [
        {
          "name": "Janssen Electronic",
          "value": "12560.0000"
        },
        {
          "name": "Referral GID",
          "value": null
        }
      ]
    }
  ]
}

i have tried to create an interface with

[Post("/{routes}/query")]
[Headers("UserName: Name", "Key: **************", "ApiIntegrationcode: *******************")]
Task<string> GetDataByUDFAsync(string routes, [Query] string udfFields = null, [Query] string query = null );

where;
routes: is the table
udfFields are fields used on filtering
query is the condition (i.e item eq ‘ABC’)

this results to an error 500