- Splitted Datetime and added Immutable versions too

src/Entity/Field/DatetimeImmutable.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace Ulmus\Entity\Field;
+
+use Ulmus\Entity\EntityObjectInterface;
+
+class DatetimeImmutable extends \DateTimeImmutable implements EntityObjectInterface {
+    use DatetimeTrait;
+}