SubscriptionAddon: fix call to undefined method Recurly_SubscriptionAddOn::__valuesString()

Author: glaubinix

Tests/Recurly/SubscriptionAddOn_Test.php

@@ -0,0 +1,10 @@
+<?php
+
+class Recurly_SubscriptionAddOn_Test extends Recurly_TestCase
+{
+    public function testToString() {
+        $addon = new \Recurly_SubscriptionAddOn();
+
+        $this->assertSame('<Recurly_SubscriptionAddOn >', $addon->__toString());
+    }
+}

lib/recurly/subscription_addon.php

@@ -55,7 +55,7 @@ protected function getChangedAttributes($nested = false) {
    */
   public function __toString() {
     $class = get_class($this);
-    $values = $this->__valuesString();
+    $values = $this->getValuesString();
     return "<$class $values>";
   }
 }