GraphQL query using Client Credentials flow in Orchard Core

Program.cs

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        
        static async Task Main(string[] args)
        {
            var httpClientHandler = new HttpClientHandler();
            httpClientHandler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;
            httpClientHandler.AutomaticDecompression = System.Net.DecompressionMethods.GZip | System.Net.DecompressionMethods.Deflate;

            var httpClient = new HttpClient(httpClientHandler);

            // https://developers.onelogin.com/openid-connect/api/client-credentials-grant

            //curl -XPOST "https://<region>.onelogin.com/oidc/token" \
            //    -H "Authorization: Basic <base64 encoded client_id:client_secret>" \
            //    -H "Content-Type: application/x-www-form-urlencoded" \
            //    -d "grant_type=client_credentials"

            string accessToken;

            using (var request = new HttpRequestMessage(HttpMethod.Post, "https://localhost:5001/connect/token"))
            {
                request.Headers.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(Encoding.UTF8.GetBytes("theclientid:theclientsecret")));
                request.Content = new StringContent("grant_type=client_credentials");
                request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");

                using (var response = await httpClient.SendAsync(request))
                {
                    var data = await response.Content.ReadAsStringAsync();

                    var doc = JsonDocument.Parse(data);
                    accessToken = doc.RootElement.GetProperty("access_token").GetString();
                }
            }

            using (var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost:5001/api/graphql?query=query%20MyQuery%20{%20blogPost%20{%20displayText%20}%20}"))
            {
                request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

                using (var response = await httpClient.SendAsync(request))
                {
                    var data = await response.Content.ReadAsStringAsync();
                    Console.WriteLine(data);
                }
            }
        }
    }
}