exampleservice.cs

public class ExampleService
{
    public HttpClient Client { get; }

    public ExampleService(HttpClient client)
    {
        client.BaseAddress = new Uri("https://api.example.com/");
        client.DefaultRequestHeaders.Add("Accept","application/json");
        client.DefaultRequestHeaders.Add("User-Agent","HttpClientFactory-Sample");
        Client = client;
    }

    public async Task<IEnumerable<User>> GetAllUsers()
    {
        var response = await Client.GetAsync(
            "/users/getall");

        response.EnsureSuccessStatusCode();

        using var responseStream = await response.Content.ReadAsStreamAsync();
        return await JsonSerializer.DeserializeAsync
            <IEnumerable<User>>(responseStream);
    }
}