GraphWebhookSubscription attribute binding error

[DDAndyChen]

I'm trying to create a function to get all subscription:

        [FunctionName("WebhookTest")]
        public static IActionResult Run(
            [HttpTrigger(AuthorizationLevel.Function, "get", Route = null)] HttpRequest req,
            [GraphWebhookSubscription] string[] subIds
            )
        {
            return new OkObjectResult("OK");
        }

I got this error in the CLI tool:

[1/18/2019 2:47:20 AM] Error indexing method 'WebhookTest.Run'
[1/18/2019 2:47:20 AM] Microsoft.Azure.WebJobs.Host: Error indexing method 'WebhookTest.Run'. System.Private.CoreLib: The given key 'T' was not present in the dictionary.

If I remove the [GraphWebhookSubscription] string[] subIds binding the function is OK.

[DDAndyChen]

This binding [GraphWebhookSubscription] Microsoft.Graph.Subscription[] subIds seems OK.