diff --git a/src/Model/Checkout/v3/GetCheckoutSessionResponse.php b/src/Model/Checkout/v3/GetCheckoutSessionResponse.php
index 9ee0533..da03069 100644
--- a/src/Model/Checkout/v3/GetCheckoutSessionResponse.php
+++ b/src/Model/Checkout/v3/GetCheckoutSessionResponse.php
@@ -11,23 +11,27 @@ class GetCheckoutSessionResponse
      * @Serializer\Type("string")
      */
     protected $sessionId;
+
     /**
-     * @var string
+     * @var string|null
      * @Serializer\Type("string")
      */
     protected $merchantSerialNumber;
+
     /**
      * @var string
      * @Serializer\Type("string")
      */
     protected $reference;
+
     /**
      * @var string
      * @Serializer\Type("string")
      */
     protected $sessionState;
+
     /**
-     * @var string
+     * @var string|null
      * @Serializer\Type("string")
      */
     protected $paymentMethod;
@@ -44,15 +48,22 @@ class GetCheckoutSessionResponse
      */
     protected $paymentDetails;
 
-
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\UserInfo
      * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\UserInfo")
      */
     protected $userInfo;
 
+    /**
+     * @var \zaporylie\Vipps\Model\Checkout\v3\ShippingDetails
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\ShippingDetails")
+     */
     protected $shippingDetails;
 
+    /**
+     * @var \zaporylie\Vipps\Model\Checkout\v3\BillingDetails
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\BillingDetails")
+     */
     protected $billingDetails;
 
     /**
diff --git a/src/Model/Checkout/v3/OrderBottomLine.php b/src/Model/Checkout/v3/OrderBottomLine.php
index 905cfbb..9e43752 100644
--- a/src/Model/Checkout/v3/OrderBottomLine.php
+++ b/src/Model/Checkout/v3/OrderBottomLine.php
@@ -33,7 +33,7 @@ class OrderBottomLine
 
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\PaymentSources|null
-     * @Serializer\Type("array<zaporylie\Vipps\Model\Checkout\v3\PaymentSources>")
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\PaymentSources")
      */
     protected $paymentSources;
 
diff --git a/src/Model/Checkout/v3/OrderLine.php b/src/Model/Checkout/v3/OrderLine.php
index a1b15e0..12e80e1 100644
--- a/src/Model/Checkout/v3/OrderLine.php
+++ b/src/Model/Checkout/v3/OrderLine.php
@@ -45,7 +45,7 @@ class OrderLine
 
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\UnitInfo
-     * @Serializer\Type("array<zaporylie\Vipps\Model\Checkout\v3\UnitInfo>")
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\UnitInfo")
      */
     protected $unitInfo;
 
diff --git a/src/Model/Checkout/v3/OtherLogisticsOption.php b/src/Model/Checkout/v3/OtherLogisticsOption.php
index c410ad5..ea2176d 100644
--- a/src/Model/Checkout/v3/OtherLogisticsOption.php
+++ b/src/Model/Checkout/v3/OtherLogisticsOption.php
@@ -9,7 +9,7 @@ class OtherLogisticsOption
 
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\Amount
-     * @Serializer\Type("array<zaporylie\Vipps\Model\Checkout\v3\OrderLine>")
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\Amount")
      */
     protected $amount;
 
diff --git a/src/Model/Checkout/v3/Transaction.php b/src/Model/Checkout/v3/Transaction.php
index dcf0342..9645437 100644
--- a/src/Model/Checkout/v3/Transaction.php
+++ b/src/Model/Checkout/v3/Transaction.php
@@ -42,7 +42,7 @@ class Transaction
      *
      * @return $this
      */
-    public function setAmount(\zaporylie\Vipps\Model\Checkout\v3\Amount $amount
+    public function setAmount(Amount $amount
     ) {
         $this->amount = $amount;
         return $this;
diff --git a/src/Model/Checkout/v3/WalletPaymentDetails.php b/src/Model/Checkout/v3/WalletPaymentDetails.php
index 612d511..e5de8f0 100644
--- a/src/Model/Checkout/v3/WalletPaymentDetails.php
+++ b/src/Model/Checkout/v3/WalletPaymentDetails.php
@@ -9,7 +9,7 @@ class WalletPaymentDetails
 
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\Amount
-     * @Serializer\Type("array<zaporylie\Vipps\Model\Checkout\v3\OrderLine>")
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\Amount")
      */
     protected $amount;
 
@@ -21,7 +21,7 @@ class WalletPaymentDetails
 
     /**
      * @var \zaporylie\Vipps\Model\Checkout\v3\Aggregate
-     * @Serializer\Type("array<zaporylie\Vipps\Model\Checkout\v3\Aggregate>")
+     * @Serializer\Type("zaporylie\Vipps\Model\Checkout\v3\Aggregate")
      */
     protected $aggregate;