Added CreatedByMyApp functionality to Invoices

Xero.Api/Core/Endpoints/InvoicesEndpoint.cs

@@ -21,6 +21,7 @@ public interface IInvoicesEndpoint : IXeroUpdateEndpoint<InvoicesEndpoint, Invoi
         IInvoicesEndpoint Statuses(IEnumerable<InvoiceStatus> statuses);
         IInvoicesEndpoint InvoiceNumbers(IEnumerable<string> invoiceNumbers);
         void EmailInvoice(Guid invoiceId);
+        IInvoicesEndpoint CreatedByMyApp();
     }
 
     public class InvoicesEndpoint
@@ -71,6 +72,11 @@ public void EmailInvoice(Guid invoiceId)
             }
         }
 
+        public IInvoicesEndpoint CreatedByMyApp()
+        {
+            return AddParameter("createdByMyApp", true);
+        }
+
         public override void ClearQueryString()
         {
             base.ClearQueryString();