support custom fields for timesheets, customers, projects and activities (#871)

src/Entity/EntityWithMetaFields.php

@@ -0,0 +1,25 @@
+<?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\Entity;
+
+use Doctrine\Common\Collections\Collection;
+
+interface EntityWithMetaFields
+{
+    /**
+     * @internal only here for symfony forms
+     * @return Collection|MetaTableTypeInterface[]
+     */
+    public function getMetaFields(): Collection;
+
+    public function getMetaField(string $name): ?MetaTableTypeInterface;
+
+    public function setMetaField(MetaTableTypeInterface $meta): EntityWithMetaFields;
+}