OCP implemented

interface BaseOperation
{
    Task<T> GetAsync<T>(string endpoint) where T : class;
}

public class HttpClientHelper : BaseOperation
{
    public async Task<T> GetAsync<T>(string endpoint) where T : class
    {
        //HttpClient implementation goes here
    }
}

public class RestSharpHelper : BaseOperation
{
    public async Task<T> GetAsync<T>(string endpoint) where T : class
    {
        //RestSharp implementation goes here
    }
}