refactor: Remove duplicate constant definition and update type hints for response properties

Author: DaanRijpkema

src/Contexts/PaymentsContext.php

@@ -28,8 +28,6 @@ class PaymentsContext extends BluemContext
 
     public const PAYMENT_METHOD_BANCONTACT = 'Bancontact';
 
-    public const PAYMENT_METHOD_BANCONTACT = 'Bancontact';
-
     public const PAYMENT_METHODS = [
         self::PAYMENT_METHOD_IDEAL,
         self::PAYMENT_METHOD_PAYPAL,

src/Requests/EmandateBluemRequest.php

@@ -10,6 +10,7 @@
 namespace Bluem\BluemPHP\Requests;
 
 use Bluem\BluemPHP\Contexts\MandatesContext;
+use Bluem\BluemPHP\Constants;
 use Bluem\BluemPHP\Helpers\BluemConfiguration;
 
 /**
@@ -90,7 +91,7 @@ public function __construct(BluemConfiguration $config, private $debtorReference
         $this->merchantID = $config->merchantID ?? "";
 
         // override with hardcoded merchantID when in test environment, according to documentation
-        if ($this->environment === BLUEM_ENVIRONMENT_TESTING) {
+        if ($this->environment === Constants::TESTING_ENVIRONMENT) {
             $this->merchantID = "0020000387";
         }
 

src/Responses/BluemResponse.php

@@ -19,9 +19,9 @@
  */
 class BluemResponse extends SimpleXMLElement implements BluemResponseInterface
 {
-    public static string $response_primary_key = null;
+    public static ?string $response_primary_key = null;
 
-    public static string $transaction_type = null;
+    public static ?string $transaction_type = null;
 
     public static ?string $error_response_type = null;
 

src/Responses/MandateTransactionBluemResponse.php

@@ -11,9 +11,9 @@
 
 class MandateTransactionBluemResponse extends TransactionBluemResponse
 {
-    public static string $transaction_type = "EMandate";
+    public static ?string $transaction_type = "EMandate";
 
-    public static string $response_primary_key = 'EMandateTransaction';
+    public static ?string $response_primary_key = 'EMandateTransaction';
 
     public static ?string $error_response_type = 'EMandateErrorResponse';