[TASK] Make module pass PHPstan checks

[TASK] Make module PSR-2 Compliant

Api/PostcodeManagementInterface.php

@@ -3,9 +3,9 @@
 /**
  * A Magento 2 module named Experius/Postcode
  * Copyright (C) 2016 Experius
- * 
+ *
  * This file included in Experius/Postcode is licensed under OSL 3.0
- * 
+ *
  * http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
  * Please see LICENSE.txt for the full text of the OSL 3.0 license
  */
@@ -14,16 +14,15 @@
 
 interface PostcodeManagementInterface
 {
-    
+
     /**
-    * Set a ponumber on the cart
-    *
-    * @param string $postcode.
-    * @param string $houseNumber
-    * @param string $houseNumberAddition
-    * @return string
-    */
-
-    public function getPostcodeInformation($postcode,$houseNumber,$houseNumberAddition);
-
+     * Set a ponumber on the cart
+     *
+     * @param  string $postcode .
+     * @param  string $houseNumber
+     * @param  string $houseNumberAddition
+     * @return string
+     */
+
+    public function getPostcodeInformation(string $postcode, string $houseNumber, string $houseNumberAddition);
 }