Agent Client using credentials json file in .NET for Dialogflow

AgentTest.cs

using System;
using Xunit;
using System.IO;
using Google.Cloud.Dialogflow.V2;
using Grpc.Core;
using Google.Apis.Auth.OAuth2;
using Grpc.Auth;

namespace dialogflowtest
{
    public class UnitTest1
    {
        [Fact]
        public void Test1()
        {
            Console.WriteLine("Starting test...");
            // Configure gRCP for a proxy server:
            //Environment.SetEnvironmentVariable("http_proxy", "http://username:password@proxy_address:80");
            //Environment.SetEnvironmentVariable("https_proxy", "https://username:password@proxy_address:443");

            // Example when loading credentials from file programatically

            // You can also set the path in an environment variable - GOOGLE_APPLICATION_CREDENTIALS, 
            // then this step would not be necessary and you could just call AgentsClient client = AgentsClient.Create();
            GoogleCredential cred = GoogleCredential.FromFile("client_credentials.json");
            Channel channel = new Channel(AgentsClient.DefaultEndpoint.Host, cred.ToChannelCredentials());
            AgentsClient client = AgentsClient.Create(channel);

            // IAM Permission Dialogflow API Admin needed for Agent
            // IAM Permission Dialogflow API Client needed for Session (intent query)
            Agent agent = client.GetAgent(new ProjectName("rjc-sandbox"));
            Console.WriteLine(agent.ToString());
            Console.WriteLine("Done.");
        }
    }
}