public async Task <ProjectTaskModel> Add(ProjectModel project, ProjectTaskModel projectTask)
        {
            var storedProject = await projectDataService.GetById(project.Id);

            // create new project task with unique id
            var mappedTask = new ProjectTask
            {
                Id = ObjectId.GenerateNewId().ToString()
            };

            // map project task model to project task and add it to the list
            projectTask.MapBack(mappedTask);
            GetProjectTasks(storedProject).Add(mappedTask);

            await projectDataService.UpdateById(storedProject.Id, storedProject);

            // map project task to project task model to get current id
            projectTask.Map(mappedTask);

            project.Tasks.Add(projectTask);

            return(projectTask);
        }