Add Webhooks in store's settings

BTCPayServer.Client/Models/WebhookInvoiceEvent.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Converters;
+
+namespace BTCPayServer.Client.Models
+{
+    public class WebhookInvoiceEvent : WebhookEvent
+    {
+        [JsonProperty(Order = 1)]
+        public string StoreId { get; set; }
+        [JsonProperty(Order = 2)]
+        public string InvoiceId { get; set; }
+    }
+}