new ProjectConstraint to add dynamic project validation (#2747)

src/Validator/Constraints/ProjectConstraint.php

@@ -0,0 +1,19 @@
+<?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\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Extend this class if you want to add dynamic project validation (eg. via a bundle).
+ */
+abstract class ProjectConstraint extends Constraint
+{
+}