Preview the Invoice to be Sent as Base64 String

var options = new RestClientOptions("https://apitest.nilvera.com")
{
    MaxTimeout = -1,
};
var client = new RestClient(options);
var request = new RestRequest("/einvoice/Send/Base64String/Preview", Method.Post);
request.AddHeader("Content-Type", "application/json");
request.AddHeader("Authorization", "Bearer <API KEY>");
var body = @"
{
  ""ZIPFileBase64"": ""string"",
  ""Alias"": ""string""
}";
request.AddJsonBody(body);
IRestResponse response = await client.ExecuteAsync(request);
Console.WriteLine(response.Content);