added invoice delete event (#3096)

src/Event/InvoiceDeleteEvent.php

@@ -0,0 +1,28 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Event;
+
+use App\Entity\Invoice;
+use Symfony\Contracts\EventDispatcher\Event;
+
+final class InvoiceDeleteEvent extends Event
+{
+    private $invoice;
+
+    public function __construct(Invoice $invoice)
+    {
+        $this->invoice = $invoice;
+    }
+
+    public function getInvoice(): Invoice
+    {
+        return $this->invoice;
+    }
+}