public AzureToSlackMiddleware(RequestDelegate next, AzureToSlackOptions options, ILoggerFactory loggerFactory)
 {
     _next    = next;
     _options = options;
     _log     = loggerFactory.CreateLogger("AzureToSlack");
 }
 public static IApplicationBuilder UseAzureToSlack(this IApplicationBuilder builder, AzureToSlackOptions options)
 {
     return builder.UseMiddleware<AzureToSlackMiddleware>(options);
 }