fix

lib/AbstractFactory/MainAbstractFactory.php

@@ -0,0 +1,20 @@
+<?php
+
+
+namespace Bx\Nullable\AbstractFactory;
+
+
+use Wt\Core\AbstractFactory\AAbstractFactory;
+use Bx\Nullable\Factory\NullableFactory;
+
+class MainAbstractFactory extends AAbstractFactory
+{
+    /**
+     * @return NullableFactory
+     */
+    public function getNullableFactory()
+    {
+        return $this->getFactoryInstance(NullableFactory::class);
+    }
+
+}