using RestSharp;


var options = new RestClientOptions("https://api.mattildapayments.com/payment-method-definitions");
var client = new RestClient(options);
var request = new RestRequest("");
request.AddHeader("Authorization", "Bearer <token>");
var response = await client.GetAsync(request);

Console.WriteLine("{0}", response.Content);

{
  "items": [
    {
      "id": "bank",
      "icon_url": "https://api.sandbox.mattildapayments.com/assets/payment-method-definitions/bank.svg",
      "display_name": "Bank",
      "long_display_name": "Bank (BACS)",
      "method": "BACS"
    }
  ]
}