HttpContext not having support for SetFeature in ASP.Net 5 RC1

HttpContext not having support for SetFeature in ASP.Net 5 RC1

 public async Task Invoke(HttpContext context)
{
   //..........//
  var errorHandlerFeature = new ErrorHandlerFeature()
                    {
                        Error = ex,
                    };
                    context.SetFeature<IErrorHandlerFeature>(errorHandlerFeature);
   //..........//
}