added drag and drop for new records via calendar (#1962)

src/Validator/ValidationException.php

@@ -0,0 +1,21 @@
+<?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\Validator;
+
+class ValidationException extends \RuntimeException
+{
+    public function __construct(string $message = null)
+    {
+        if ($message === null) {
+            $message = 'Validation failed';
+        }
+        parent::__construct($message, 400);
+    }
+}