Rename Collection class to BaseCollection. Add BaseCollection::isValidType() method to validate type of element before add it to collection. Add BaseCollection ::prepareElements() method to allow preparation of elements in custom way.

tests/Utilities/Reflection/ObjectsCollection.php

@@ -0,0 +1,34 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Meritoo\Test\Common\Utilities\Reflection;
+
+use Meritoo\Common\Collection\BaseCollection;
+
+/**
+ * Collection of objects
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ *
+ * @internal
+ * @coversNothing
+ */
+class ObjectsCollection extends BaseCollection
+{
+    protected function isValidType($element): bool
+    {
+        return $element instanceof A
+            || $element instanceof B
+            || $element instanceof C
+            || $element instanceof D
+            || $element instanceof F;
+    }
+}