refactored State pattern example

Behavioral/State/StateDone.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace DesignPatterns\Behavioral\State;
+
+class StateDone implements State
+{
+    public function proceedToNext(OrderContext $context)
+    {
+        // there is nothing more to do
+    }
+
+    public function toString(): string
+    {
+        return 'done';
+    }
+}