ASP .NET Core Dependency Injection (RestClient.Net)

DI.cs

var serviceCollection = new ServiceCollection()
    //Add a service which has an IClient dependency
    .AddSingleton<IGetString, GetString1>()
    //Add RestClient.Net with a default Base Url of http://www.test.com
    .AddRestClient((o) => o.BaseUrl = "http://www.test.com".ToAbsoluteUrl());

//Use HttpClient dependency injection
_ = serviceCollection.AddHttpClient();