private static void AddTask()
{
    using (ProjectContext projContext = new ProjectContext("https://nakkeerann.sharepoint.com/sites/pwa"))
    {
        projContext.Credentials = new SharePointOnlineCredentials("nav@nakkeerann.onmicrosoft.com", password);
        var projects = projContext.Projects;
        var projectId = "3a000b01-55f2-e811-afac-00155d24c70d";
        var project = projects.GetById(projectId);
        project.CheckOut();
        var draftProject = project.Draft;
        var tasks = draftProject.Tasks;
        TaskCreationInformation newTask = new TaskCreationInformation();
        newTask.Name = "Task4";
        //newTask["a"] = "";
        tasks.Add(newTask);
        draftProject.Update();
        draftProject.Publish(true);
        projContext.ExecuteQuery();

        Console.WriteLine("Task Created: " + newTask.Name);
                
    }
}