Custom action implementation using IHttpActionResult

CustomActionResult.cs

public class CustomActionResult : IHttpActionResult
    {
        private HttpStatusCode _statusCode { get; set; }
        private string _message { get; set; }
        private Exception _exception { get; set; }

        public CustomActionResult(HttpStatusCode statusCode, string errorMessage) : this(statusCode, errorMessage, null)
        {}

        public CustomActionResult(HttpStatusCode statusCode, string errorMessage, Exception exception)
        {
            _statusCode = statusCode;
            _message = errorMessage;
            _exception = exception;
        }

        public Task<HttpResponseMessage> ExecuteAsync(System.Threading.CancellationToken cancellationToken)
        {
            HttpResponseMessage response = new HttpResponseMessage(_statusCode);
            StringBuilder stringBldr = new StringBuilder();
            stringBldr.Append(_message);

            if (_exception != null)
            {
                stringBldr.Append(_exception.ToString());
            }

            response.Content = new StringContent(stringBldr.ToString());
            return Task.FromResult(response);
        }
    }

CustomNotFoundActionResult.cs

 public class CustomNotFoundActionResult : CustomActionResult
    {
        public CustomNotFoundActionResult(string errorMessage)
            : this(errorMessage, null)
        {}

        public CustomNotFoundActionResult(string errorMessage, Exception exception)
            : base(HttpStatusCode.NotFound, errorMessage, exception)
        {}
    }

GenericApiController.cs

    public class GenericApiController : ApiController
    {
        private NamedLogger _logger = null;
        protected NamedLogger Log
        {
            get
            {
                if (_logger == null)
                {
                    _logger = new NamedLogger(GetType().Name);
                }
                return _logger;
            }
        }

        public virtual IHttpActionResult CustomNotFoundResult(string errorMessage)
        {
            return this.CustomNotFoundResult(errorMessage, null);
        }

        public virtual IHttpActionResult CustomNotFoundResult(string errorMessage, Exception exception)
        {
            CustomNotFoundActionResult result = new CustomNotFoundActionResult(errorMessage, exception);
            return result;
        }
    }