diff --git a/src/Model/MailingList/CreateResponse.php b/src/Model/MailingList/CreateResponse.php
index 0f62ad5..14e8a09 100644
--- a/src/Model/MailingList/CreateResponse.php
+++ b/src/Model/MailingList/CreateResponse.php
@@ -15,45 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class CreateResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $message;
-
-    /**
-     * @var MailingList
-     */
     private $list;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $message = isset($data['message']) ? $data['message'] : '';
-        $list = MailingList::create($data['list']);
+        $model = new self();
+        $model->list = MailingList::create($data['list']);
+        $model->message = $data['message'] ?? '';
 
-        return new self($list, $message);
+        return $model;
     }
 
-    private function __construct(MailingList $list, $message)
+    private function __construct()
     {
-        $this->list = $list;
-        $this->message = $message;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
 
-    /**
-     * @return MailingList
-     */
-    public function getList()
+    public function getList(): MailingList
     {
         return $this->list;
     }
diff --git a/src/Model/MailingList/DeleteResponse.php b/src/Model/MailingList/DeleteResponse.php
index ddd64ef..f503387 100644
--- a/src/Model/MailingList/DeleteResponse.php
+++ b/src/Model/MailingList/DeleteResponse.php
@@ -15,48 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class DeleteResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $message;
-
-    /**
-     * @var string
-     */
     private $address;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $message = isset($data['message']) ? $data['message'] : '';
-        $address = isset($data['address']) ? $data['address'] : '';
+        $model = new self();
+        $model->address = $data['address'] ?? '';
+        $model->message = $data['message'] ?? '';
 
-        return new self($address, $message);
+        return $model;
     }
 
-    /**
-     * DeleteResponse constructor.
-     *
-     * @param string $address
-     * @param string $message
-     */
-    private function __construct($address, $message)
+    private function __construct()
     {
-        $this->address = $address;
-        $this->message = $message;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
 
-    /**
-     * @return string
-     */
-    public function getAddress()
+    public function getAddress(): string
     {
         return $this->address;
     }
diff --git a/src/Model/MailingList/MailingList.php b/src/Model/MailingList/MailingList.php
index 4868223..801c167 100644
--- a/src/Model/MailingList/MailingList.php
+++ b/src/Model/MailingList/MailingList.php
@@ -15,114 +15,56 @@ use Mailgun\Model\ApiResponse;
 
 final class MailingList implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $name;
-
-    /**
-     * @var string
-     */
     private $address;
-
-    /**
-     * @var string
-     */
     private $accessLevel;
-
-    /**
-     * @var string
-     */
     private $description;
-
-    /**
-     * @var int
-     */
     private $membersCount;
-
-    /**
-     * @var \DateTime
-     */
     private $createdAt;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        return new self(
-            isset($data['name']) ? $data['name'] : null,
-            isset($data['address']) ? $data['address'] : null,
-            isset($data['access_level']) ? $data['access_level'] : null,
-            isset($data['description']) ? $data['description'] : null,
-            isset($data['members_count']) ? $data['members_count'] : null,
-            isset($data['created_at']) ? new \DateTime($data['created_at']) : null
-        );
+        $model = new self();
+        $model->name = $data['name'] ?? null;
+        $model->address = $data['address'] ?? null;
+        $model->accessLevel = $data['access_level'] ?? null;
+        $model->description = $data['description'] ?? null;
+        $model->membersCount = (int) ($data['members_count'] ?? 0);
+        $model->createdAt = isset($data['created_at']) ? new \DateTimeImmutable($data['created_at']) : null;
+
+        return $model;
     }
 
-    /**
-     * MailingList constructor.
-     *
-     * @param string $name
-     * @param string $address
-     * @param string $accessLevel
-     * @param string $description
-     * @param int    $membersCount
-     */
-    private function __construct($name, $address, $accessLevel, $description, $membersCount, \DateTime $createdAt)
+    private function __construct()
     {
-        $this->name = $name;
-        $this->address = $address;
-        $this->accessLevel = $accessLevel;
-        $this->description = $description;
-        $this->membersCount = $membersCount;
-        $this->createdAt = $createdAt;
     }
 
-    /**
-     * @return string
-     */
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
 
-    /**
-     * @return string
-     */
-    public function getAddress()
+    public function getAddress(): ?string
     {
         return $this->address;
     }
 
-    /**
-     * @return string
-     */
-    public function getAccessLevel()
+    public function getAccessLevel(): ?string
     {
         return $this->accessLevel;
     }
 
-    /**
-     * @return string
-     */
-    public function getDescription()
+    public function getDescription(): ?string
     {
         return $this->description;
     }
 
-    /**
-     * @return int
-     */
-    public function getMembersCount()
+    public function getMembersCount(): int
     {
         return $this->membersCount;
     }
 
-    /**
-     * @return \DateTime
-     */
-    public function getCreatedAt()
+    public function getCreatedAt(): \DateTimeImmutable
     {
         return $this->createdAt;
     }
diff --git a/src/Model/MailingList/Member/CreateResponse.php b/src/Model/MailingList/Member/CreateResponse.php
index 33dd4ef..bfff039 100644
--- a/src/Model/MailingList/Member/CreateResponse.php
+++ b/src/Model/MailingList/Member/CreateResponse.php
@@ -15,47 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class CreateResponse implements ApiResponse
 {
-    /**
-     * @var Member
-     */
     private $member;
-
-    /**
-     * @var string
-     */
     private $message;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $member = Member::create($data['member']);
-        $message = isset($data['message']) ? $data['message'] : '';
+        $model = new self();
+        $model->member = Member::create($data['member']);
+        $model->message = $data['message'] ?? '';
 
-        return new self($member, $message);
+        return $model;
     }
 
-    /**
-     * CreateMemberResponse constructor.
-     *
-     * @param string $message
-     */
-    private function __construct(Member $member, $message)
+    private function __construct()
     {
-        $this->member = $member;
-        $this->message = $message;
     }
 
-    /**
-     * @return Member
-     */
-    public function getMember()
+    public function getMember(): Member
     {
         return $this->member;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
diff --git a/src/Model/MailingList/Member/DeleteResponse.php b/src/Model/MailingList/Member/DeleteResponse.php
index 8acd17c..44ac252 100644
--- a/src/Model/MailingList/Member/DeleteResponse.php
+++ b/src/Model/MailingList/Member/DeleteResponse.php
@@ -15,47 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class DeleteResponse implements ApiResponse
 {
-    /**
-     * @var Member
-     */
     private $member;
-
-    /**
-     * @var string
-     */
     private $message;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $member = Member::create($data['member']);
-        $message = isset($data['message']) ? $data['message'] : '';
+        $model = new self();
+        $model->member = Member::create($data['member']);
+        $model->message = $data['message'] ?? '';
 
-        return new self($member, $message);
+        return $model;
     }
 
-    /**
-     * DeleteMemberResponse constructor.
-     *
-     * @param string $message
-     */
-    private function __construct(Member $member, $message)
+    private function __construct()
     {
-        $this->member = $member;
-        $this->message = $message;
     }
 
-    /**
-     * @return Member
-     */
-    public function getMember()
+    public function getMember(): Member
     {
         return $this->member;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
diff --git a/src/Model/MailingList/Member/IndexResponse.php b/src/Model/MailingList/Member/IndexResponse.php
index e3377fe..b3c9842 100644
--- a/src/Model/MailingList/Member/IndexResponse.php
+++ b/src/Model/MailingList/Member/IndexResponse.php
@@ -24,10 +24,7 @@ final class IndexResponse implements ApiResponse, PagingProvider
      */
     private $items;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
         $items = [];
 
@@ -37,22 +34,21 @@ final class IndexResponse implements ApiResponse, PagingProvider
             }
         }
 
-        return new self($items, $data['paging']);
+        $model = new self();
+        $model->items = $items;
+        $model->paging = $data['paging'];
+
+        return $model;
     }
 
-    /**
-     * @param Member[] $items
-     */
-    private function __construct(array $items, array $paging)
+    private function __construct()
     {
-        $this->items = $items;
-        $this->paging = $paging;
     }
 
     /**
      * @return Member[]
      */
-    public function getItems()
+    public function getItems(): array
     {
         return $this->items;
     }
diff --git a/src/Model/MailingList/Member/Member.php b/src/Model/MailingList/Member/Member.php
index fe6e9e7..1c7a035 100644
--- a/src/Model/MailingList/Member/Member.php
+++ b/src/Model/MailingList/Member/Member.php
@@ -15,75 +15,42 @@ use Mailgun\Model\ApiResponse;
 
 final class Member implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $name;
-
-    /**
-     * @var string
-     */
     private $address;
-
-    /**
-     * @var array
-     */
     private $vars;
-
-    /**
-     * @var bool
-     */
     private $subscribed;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        return new self(
-            isset($data['name']) ? $data['name'] : null,
-            isset($data['address']) ? $data['address'] : null,
-            isset($data['vars']) ? $data['vars'] : [],
-            isset($data['subscribed']) ? (bool) $data['subscribed'] : null
-        );
+        $model = new self();
+        $model->name = $data['name'] ?? null;
+        $model->address = $data['address'] ?? null;
+        $model->vars = $data['vars'] ?? [];
+        $model->subscribed = $data['subscribed'] ?? null;
+
+        return $model;
     }
 
-    private function __construct($name, $address, $vars = [], $subscribed = null)
+    private function __construct()
     {
-        $this->name = $name;
-        $this->address = $address;
-        $this->vars = $vars;
-        $this->subscribed = $subscribed;
     }
 
-    /**
-     * @return string
-     */
-    public function getName()
+    public function getName(): ?string
     {
         return $this->name;
     }
 
-    /**
-     * @return string
-     */
-    public function getAddress()
+    public function getAddress(): ?string
     {
         return $this->address;
     }
 
-    /**
-     * @return array
-     */
-    public function getVars()
+    public function getVars(): array
     {
         return $this->vars;
     }
 
-    /**
-     * @return bool
-     */
-    public function isSubscribed()
+    public function isSubscribed(): ?bool
     {
         return $this->subscribed;
     }
diff --git a/src/Model/MailingList/Member/ShowResponse.php b/src/Model/MailingList/Member/ShowResponse.php
index b65fc69..3ca8534 100644
--- a/src/Model/MailingList/Member/ShowResponse.php
+++ b/src/Model/MailingList/Member/ShowResponse.php
@@ -15,27 +15,21 @@ use Mailgun\Model\ApiResponse;
 
 final class ShowResponse implements ApiResponse
 {
-    /**
-     * @var Member
-     */
     private $member;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $member = Member::create($data['member']);
+        $model = new self();
+        $model->member = Member::create($data['member']);
 
-        return new self($member);
+        return $model;
     }
 
-    private function __construct(Member $member)
+    private function __construct()
     {
-        $this->member = $member;
     }
 
-    /**
-     * @return Member
-     */
-    public function getMember()
+    public function getMember(): Member
     {
         return $this->member;
     }
diff --git a/src/Model/MailingList/Member/UpdateResponse.php b/src/Model/MailingList/Member/UpdateResponse.php
index e017caf..dd17011 100644
--- a/src/Model/MailingList/Member/UpdateResponse.php
+++ b/src/Model/MailingList/Member/UpdateResponse.php
@@ -15,47 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class UpdateResponse implements ApiResponse
 {
-    /**
-     * @var Member
-     */
     private $member;
-
-    /**
-     * @var string
-     */
     private $message;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $member = Member::create($data['member']);
-        $message = isset($data['message']) ? $data['message'] : '';
+        $model = new self();
+        $model->member = Member::create($data['member']);
+        $model->message = $data['message'] ?? '';
 
-        return new self($member, $message);
+        return $model;
     }
 
-    /**
-     * UpdateMemberResponse constructor.
-     *
-     * @param string $message
-     */
-    private function __construct(Member $member, $message)
+    private function __construct()
     {
-        $this->member = $member;
-        $this->message = $message;
     }
 
-    /**
-     * @return Member
-     */
-    public function getMember()
+    public function getMember(): Member
     {
         return $this->member;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
diff --git a/src/Model/MailingList/PagesResponse.php b/src/Model/MailingList/PagesResponse.php
index a0e605f..78745c9 100644
--- a/src/Model/MailingList/PagesResponse.php
+++ b/src/Model/MailingList/PagesResponse.php
@@ -19,9 +19,6 @@ final class PagesResponse implements ApiResponse, PagingProvider
 {
     use PaginationResponse;
 
-    /**
-     * @var MailingList[]
-     */
     private $items;
 
     /**
@@ -37,22 +34,21 @@ final class PagesResponse implements ApiResponse, PagingProvider
             }
         }
 
-        return new self($items, $data['paging']);
+        $model = new self();
+        $model->items = $items;
+        $model->paging = $data['paging'];
+
+        return $model;
     }
 
-    /**
-     * @param MailingList[] $items
-     */
-    private function __construct(array $items, array $paging)
+    private function __construct()
     {
-        $this->items = $items;
-        $this->paging = $paging;
     }
 
     /**
      * @return MailingList[]
      */
-    public function getLists()
+    public function getLists(): array
     {
         return $this->items;
     }
diff --git a/src/Model/MailingList/ShowResponse.php b/src/Model/MailingList/ShowResponse.php
index 922cefe..5280a38 100644
--- a/src/Model/MailingList/ShowResponse.php
+++ b/src/Model/MailingList/ShowResponse.php
@@ -15,27 +15,21 @@ use Mailgun\Model\ApiResponse;
 
 final class ShowResponse implements ApiResponse
 {
-    /**
-     * @var MailingList
-     */
     private $list;
 
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $list = MailingList::create($data['list']);
+        $model = new self();
+        $model->list = MailingList::create($data['list']);
 
-        return new self($list);
+        return $model;
     }
 
-    private function __construct(MailingList $list)
+    private function __construct()
     {
-        $this->list = $list;
     }
 
-    /**
-     * @return MailingList
-     */
-    public function getList()
+    public function getList(): MailingList
     {
         return $this->list;
     }
diff --git a/src/Model/MailingList/UpdateResponse.php b/src/Model/MailingList/UpdateResponse.php
index e30d0e6..f7a29ba 100644
--- a/src/Model/MailingList/UpdateResponse.php
+++ b/src/Model/MailingList/UpdateResponse.php
@@ -15,45 +15,28 @@ use Mailgun\Model\ApiResponse;
 
 final class UpdateResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $message;
-
-    /**
-     * @var MailingList
-     */
     private $list;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $message = isset($data['message']) ? $data['message'] : '';
-        $list = MailingList::create($data['list']);
+        $model = new self();
+        $model->list = MailingList::create($data['list']);
+        $model->message = $data['message'] ?? '';
 
-        return new self($list, $message);
+        return $model;
     }
 
-    private function __construct(MailingList $list, $message)
+    private function __construct()
     {
-        $this->list = $list;
-        $this->message = $message;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
 
-    /**
-     * @return MailingList
-     */
-    public function getList()
+    public function getList(): MailingList
     {
         return $this->list;
     }
diff --git a/src/Model/Message/SendResponse.php b/src/Model/Message/SendResponse.php
index a8cc147..f729a68 100644
--- a/src/Model/Message/SendResponse.php
+++ b/src/Model/Message/SendResponse.php
@@ -18,56 +18,28 @@ use Mailgun\Model\ApiResponse;
  */
 final class SendResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $id;
-
-    /**
-     * @var string
-     */
     private $message;
 
-    /**
-     * @param string $id
-     * @param string $message
-     */
-    private function __construct($id, $message)
+    private function __construct()
     {
-        $this->id = $id;
-        $this->message = $message;
     }
 
-    /**
-     * @return SendResponse
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $id = '';
-        $message = '';
+        $model = new self();
+        $model->id = $data['id'] ?? '';
+        $model->message = $data['message'] ?? '';
 
-        if (isset($data['id'])) {
-            $id = $data['id'];
-        }
-        if (isset($data['message'])) {
-            $message = $data['message'];
-        }
-
-        return new self($id, $message);
+        return $model;
     }
 
-    /**
-     * @return string
-     */
-    public function getId()
+    public function getId(): string
     {
         return $this->id;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): string
     {
         return $this->message;
     }
diff --git a/src/Model/Message/ShowResponse.php b/src/Model/Message/ShowResponse.php
index feee5bb..52451c4 100644
--- a/src/Model/Message/ShowResponse.php
+++ b/src/Model/Message/ShowResponse.php
@@ -18,382 +18,126 @@ use Mailgun\Model\ApiResponse;
  */
 final class ShowResponse implements ApiResponse
 {
-    /**
-     * Only available with message/rfc2822.
-     *
-     * @var string
-     */
     private $recipient;
-
-    /**
-     * Only available with message/rfc2822.
-     *
-     * @var string
-     */
     private $bodyMime;
-
-    /**
-     * @var string
-     */
     private $recipients;
-
-    /**
-     * @var string
-     */
     private $sender;
-
-    /**
-     * @var string
-     */
     private $from;
-
-    /**
-     * @var string
-     */
     private $subject;
-
-    /**
-     * @var string
-     */
     private $bodyPlain;
-
-    /**
-     * @var string
-     */
     private $strippedText;
-
-    /**
-     * @var string
-     */
     private $strippedSignature;
-
-    /**
-     * @var string
-     */
     private $bodyHtml;
-
-    /**
-     * @var string
-     */
     private $strippedHtml;
-
-    /**
-     * @var array
-     */
     private $attachments;
-
-    /**
-     * @var string
-     */
     private $messageUrl;
-
-    /**
-     * @var string
-     */
     private $contentIdMap;
-
-    /**
-     * @var array
-     */
     private $messageHeaders;
 
-    /**
-     * Do not let this object be creted without the ::create.
-     */
     private function __construct()
     {
     }
 
-    /**
-     * @return ShowResponse
-     */
-    public static function create(array $data)
+    public static function create(array $data): array
     {
-        $response = new self();
+        $model = new self();
+        $model->recipients = $data['recipients'] ?? null;
+        $model->sender = $data['sender'] ?? null;
+        $model->from = $data['from'] ?? null;
+        $model->subject = $data['subject'] ?? null;
+        $model->bodyPlain = $data['body-plain'] ?? null;
+        $model->strippedText = $data['stripped-text'] ?? null;
+        $model->strippedSignature = $data['stripped-signature'] ?? null;
+        $model->bodyHtml = $data['body-html'] ?? null;
+        $model->strippedHtml = $data['stripped-html'] ?? null;
+        $model->messageUrl = $data['message-url'] ?? null;
+        $model->messageHeaders = $data['message-headers'] ?? null;
+        $model->recipient = $data['recipient'] ?? null;
+        $model->bodyMime = $data['body-mime'] ?? null;
+        $model->attachments = $data['attachments'] ?? [];
+        $model->contentIdMap = $data['content-id-map'] ?? null;
 
-        if (isset($data['recipients'])) {
-            $response->setRecipients($data['recipients']);
-        }
-        if (isset($data['sender'])) {
-            $response->setSender($data['sender']);
-        }
-        if (isset($data['from'])) {
-            $response->setFrom($data['from']);
-        }
-        if (isset($data['subject'])) {
-            $response->setSubject($data['subject']);
-        }
-        if (isset($data['body-plain'])) {
-            $response->setBodyPlain($data['body-plain']);
-        }
-        if (isset($data['stripped-text'])) {
-            $response->setStrippedText($data['stripped-text']);
-        }
-        if (isset($data['stripped-signature'])) {
-            $response->setStrippedSignature($data['stripped-signature']);
-        }
-        if (isset($data['body-html'])) {
-            $response->setBodyHtml($data['body-html']);
-        }
-        if (isset($data['stripped-html'])) {
-            $response->setStrippedHtml($data['stripped-html']);
-        }
-        if (isset($data['message-url'])) {
-            $response->setMessageUrl($data['message-url']);
-        }
-        if (isset($data['message-headers'])) {
-            $response->setMessageHeaders($data['message-headers']);
-        }
-        if (isset($data['recipient'])) {
-            $response->setRecipient($data['recipient']);
-        }
-        if (isset($data['body-mime'])) {
-            $response->setBodyMime($data['body-mime']);
-        }
-        if (isset($data['attachments'])) {
-            $response->setAttachments($data['attachments']);
-        }
-        if (isset($data['content-id-map'])) {
-            $response->setContentIdMap($data['content-id-map']);
-        }
-
-        return $response;
+        return $model;
     }
 
     /**
-     * @return string
+     * Only available with message/rfc2822.
      */
-    public function getRecipient()
+    public function getRecipient(): ?string
     {
         return $this->recipient;
     }
 
     /**
-     * @param string $recipient
+     * Only available with message/rfc2822.
      */
-    private function setRecipient($recipient)
-    {
-        $this->recipient = $recipient;
-    }
-
-    /**
-     * @return string
-     */
-    public function getBodyMime()
+    public function getBodyMime(): ?string
     {
         return $this->bodyMime;
     }
 
-    /**
-     * @param string $bodyMime
-     */
-    private function setBodyMime($bodyMime)
-    {
-        $this->bodyMime = $bodyMime;
-    }
-
-    /**
-     * @return string
-     */
-    public function getRecipients()
+    public function getRecipients(): ?string
     {
         return $this->recipients;
     }
 
-    /**
-     * @param string $recipients
-     */
-    private function setRecipients($recipients)
-    {
-        $this->recipients = $recipients;
-    }
-
-    /**
-     * @return string
-     */
-    public function getSender()
+    public function getSender(): ?string
     {
         return $this->sender;
     }
 
-    /**
-     * @param string $sender
-     */
-    private function setSender($sender)
-    {
-        $this->sender = $sender;
-    }
-
-    /**
-     * @return string
-     */
-    public function getFrom()
+    public function getFrom(): ?string
     {
         return $this->from;
     }
 
-    /**
-     * @param string $from
-     */
-    private function setFrom($from)
-    {
-        $this->from = $from;
-    }
-
-    /**
-     * @return string
-     */
-    public function getSubject()
+    public function getSubject(): ?string
     {
         return $this->subject;
     }
 
-    /**
-     * @param string $subject
-     */
-    private function setSubject($subject)
-    {
-        $this->subject = $subject;
-    }
-
-    /**
-     * @return string
-     */
-    public function getBodyPlain()
+    public function getBodyPlain(): ?string
     {
         return $this->bodyPlain;
     }
 
-    /**
-     * @param string $bodyPlain
-     */
-    private function setBodyPlain($bodyPlain)
-    {
-        $this->bodyPlain = $bodyPlain;
-    }
-
-    /**
-     * @return string
-     */
-    public function getStrippedText()
+    public function getStrippedText(): ?string
     {
         return $this->strippedText;
     }
 
-    /**
-     * @param string $strippedText
-     */
-    private function setStrippedText($strippedText)
-    {
-        $this->strippedText = $strippedText;
-    }
-
-    /**
-     * @return string
-     */
-    public function getStrippedSignature()
+    public function getStrippedSignature(): ?string
     {
         return $this->strippedSignature;
     }
 
-    /**
-     * @param string $strippedSignature
-     */
-    private function setStrippedSignature($strippedSignature)
-    {
-        $this->strippedSignature = $strippedSignature;
-    }
-
-    /**
-     * @return string
-     */
-    public function getBodyHtml()
+    public function getBodyHtml(): ?string
     {
         return $this->bodyHtml;
     }
 
-    /**
-     * @param string $bodyHtml
-     */
-    private function setBodyHtml($bodyHtml)
-    {
-        $this->bodyHtml = $bodyHtml;
-    }
-
-    /**
-     * @return string
-     */
-    public function getStrippedHtml()
+    public function getStrippedHtml(): ?string
     {
         return $this->strippedHtml;
     }
 
-    /**
-     * @param string $strippedHtml
-     */
-    private function setStrippedHtml($strippedHtml)
-    {
-        $this->strippedHtml = $strippedHtml;
-    }
-
-    /**
-     * @return array
-     */
-    public function getAttachments()
+    public function getAttachments(): array
     {
         return $this->attachments;
     }
 
-    /**
-     * @param array $attachments
-     */
-    private function setAttachments($attachments)
-    {
-        $this->attachments = $attachments;
-    }
-
-    /**
-     * @return string
-     */
-    public function getMessageUrl()
+    public function getMessageUrl(): ?string
     {
         return $this->messageUrl;
     }
 
-    /**
-     * @param string $messageUrl
-     */
-    private function setMessageUrl($messageUrl)
-    {
-        $this->messageUrl = $messageUrl;
-    }
-
-    /**
-     * @return string
-     */
-    public function getContentIdMap()
+    public function getContentIdMap(): ?string
     {
         return $this->contentIdMap;
     }
 
-    /**
-     * @param string $contentIdMap
-     */
-    public function setContentIdMap($contentIdMap)
-    {
-        $this->contentIdMap = $contentIdMap;
-    }
-
-    /**
-     * @return array
-     */
-    public function getMessageHeaders()
+    public function getMessageHeaders(): array
     {
         return $this->messageHeaders;
     }
-
-    private function setMessageHeaders(array $messageHeaders)
-    {
-        $this->messageHeaders = $messageHeaders;
-    }
 }
diff --git a/src/Model/Route/Action.php b/src/Model/Route/Action.php
index 134ec63..3cced6a 100644
--- a/src/Model/Route/Action.php
+++ b/src/Model/Route/Action.php
@@ -16,9 +16,6 @@ namespace Mailgun\Model\Route;
  */
 final class Action
 {
-    /**
-     * @var string
-     */
     private $action;
 
     /**
@@ -42,10 +39,7 @@ final class Action
         $this->action = $action;
     }
 
-    /**
-     * @return string
-     */
-    public function getAction()
+    public function getAction(): string
     {
         return $this->action;
     }
diff --git a/src/Model/Route/CreateResponse.php b/src/Model/Route/CreateResponse.php
index 99a2d20..7b7c1f0 100644
--- a/src/Model/Route/CreateResponse.php
+++ b/src/Model/Route/CreateResponse.php
@@ -18,50 +18,28 @@ use Mailgun\Model\ApiResponse;
  */
 final class CreateResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $message;
-
-    /**
-     * @var Route
-     */
     private $route;
 
-    /**
-     * {@inheritdoc}
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $message = isset($data['message']) ? $data['message'] : null;
-        $route = isset($data['route']) ? Route::create($data['route']) : null;
+        $model = new self();
+        $model->message = $data['message'] ?? null;
+        $model->route = isset($data['id']) ? Route::create($data) : null;
 
-        return new self($message, $route);
+        return $model;
     }
 
-    /**
-     * CreateResponse Private Constructor.
-     *
-     * @param string|null $message
-     */
-    private function __construct($message = null, Route $route = null)
+    private function __construct()
     {
-        $this->message = $message;
-        $this->route = $route;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): ?string
     {
         return $this->message;
     }
 
-    /**
-     * @return Route
-     */
-    public function getRoute()
+    public function getRoute(): ?Route
     {
         return $this->route;
     }
diff --git a/src/Model/Route/DeleteResponse.php b/src/Model/Route/DeleteResponse.php
index 5b4e3a3..b9575cd 100644
--- a/src/Model/Route/DeleteResponse.php
+++ b/src/Model/Route/DeleteResponse.php
@@ -18,49 +18,28 @@ use Mailgun\Model\ApiResponse;
  */
 final class DeleteResponse implements ApiResponse
 {
-    /**
-     * @var string
-     */
     private $message;
-
-    /**
-     * @var string
-     */
     private $error;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        return new self(
-            isset($data['message']) ? $data['message'] : null,
-            isset($data['error']) ? $data['error'] : null
-        );
+        $model = new self();
+        $model->message = $data['message'] ?? null;
+        $model->error = $data['error'] ?? null;
+
+        return $model;
     }
 
-    /**
-     * @param string $message
-     * @param string $error
-     */
-    private function __construct($message, $error)
+    private function __construct()
     {
-        $this->message = $message;
-        $this->error = $error;
     }
 
-    /**
-     * @return string
-     */
-    public function getMessage()
+    public function getMessage(): ?string
     {
         return $this->message;
     }
 
-    /**
-     * @return string
-     */
-    public function getError()
+    public function getError(): ?string
     {
         return $this->error;
     }
diff --git a/src/Model/Route/IndexResponse.php b/src/Model/Route/IndexResponse.php
index dc12eed..5bdf170 100644
--- a/src/Model/Route/IndexResponse.php
+++ b/src/Model/Route/IndexResponse.php
@@ -18,20 +18,10 @@ use Mailgun\Model\ApiResponse;
  */
 final class IndexResponse implements ApiResponse
 {
-    /**
-     * @var int
-     */
     private $totalCount;
-
-    /**
-     * @var Route[]
-     */
     private $items;
 
-    /**
-     * {@inheritdoc}
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
         $items = [];
 
@@ -41,29 +31,18 @@ final class IndexResponse implements ApiResponse
             }
         }
 
-        if (isset($data['total_count'])) {
-            $count = $data['total_count'];
-        } else {
-            $count = count($items);
-        }
+        $model = new self();
+        $model->items = $items;
+        $model->totalCount = (int) ($data['total_count'] ?? count($items));
 
-        return new self($count, $items);
+        return $model;
     }
 
-    /**
-     * @param int     $totalCount
-     * @param Route[] $items
-     */
-    private function __construct($totalCount, array $items)
+    private function __construct()
     {
-        $this->totalCount = $totalCount;
-        $this->items = $items;
     }
 
-    /**
-     * @return int
-     */
-    public function getTotalCount()
+    public function getTotalCount(): int
     {
         return $this->totalCount;
     }
@@ -71,7 +50,7 @@ final class IndexResponse implements ApiResponse
     /**
      * @return Route[]
      */
-    public function getRoutes()
+    public function getRoutes(): array
     {
         return $this->items;
     }
diff --git a/src/Model/Route/Route.php b/src/Model/Route/Route.php
index ff945f4..5679712 100644
--- a/src/Model/Route/Route.php
+++ b/src/Model/Route/Route.php
@@ -16,78 +16,31 @@ namespace Mailgun\Model\Route;
  */
 final class Route
 {
-    /**
-     * @var string
-     */
     private $id;
-
-    /**
-     * @var int
-     */
     private $priority;
-
-    /**
-     * @var string
-     */
     private $filter;
-
-    /**
-     * @var Action[]
-     */
     private $actions;
-
-    /**
-     * @var string
-     */
     private $description;
-
-    /**
-     * @var \DateTime
-     */
     private $createdAt;
 
-    /**
-     * Route Named Constructor.
-     *
-     *
-     * @return Route
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        return new self(
-            isset($data['id']) ? $data['id'] : null,
-            isset($data['priority']) ? $data['priority'] : null,
-            isset($data['expression']) ? $data['expression'] : null,
-            isset($data['actions']) ? $data['actions'] : [],
-            isset($data['description']) ? $data['description'] : null,
-            isset($data['created_at']) ? new \DateTime($data['created_at']) : null
-        );
+        $model = new self();
+        $model->id = $data['id'] ?? null;
+        $model->priority = $data['priority'] ?? null;
+        $model->filter = $data['expression'] ?? null;
+        $model->actions = Action::createMultiple($data['actions'] ?? []);
+        $model->description = $data['description'] ?? null;
+        $model->createdAt = isset($data['created_at']) ? new \DateTimeImmutable($data['created_at']) : null;
+
+        return $model;
     }
 
-    /**
-     * Route Private Constructor.
-     *
-     * @param string    $id
-     * @param int       $priority
-     * @param string    $expression
-     * @param array     $actions
-     * @param string    $description
-     * @param \DateTime $createdAt
-     */
-    private function __construct($id, $priority, $expression, $actions, $description, \DateTime $createdAt = null)
+    private function __construct()
     {
-        $this->id = $id;
-        $this->priority = $priority;
-        $this->filter = $expression;
-        $this->actions = Action::createMultiple($actions);
-        $this->description = $description;
-        $this->createdAt = $createdAt;
     }
 
-    /**
-     * @return string
-     */
-    public function getId()
+    public function getId(): ?string
     {
         return $this->id;
     }
@@ -95,39 +48,27 @@ final class Route
     /**
      * @return Action[]
      */
-    public function getActions()
+    public function getActions(): array
     {
         return $this->actions;
     }
 
-    /**
-     * @return string
-     */
-    public function getDescription()
+    public function getDescription(): ?string
     {
         return $this->description;
     }
 
-    /**
-     * @return string
-     */
-    public function getFilter()
+    public function getFilter(): ?string
     {
         return $this->filter;
     }
 
-    /**
-     * @return int
-     */
-    public function getPriority()
+    public function getPriority(): ?int
     {
         return $this->priority;
     }
 
-    /**
-     * @return \DateTime
-     */
-    public function getCreatedAt()
+    public function getCreatedAt(): \DateTimeImmutable
     {
         return $this->createdAt;
     }
diff --git a/src/Model/Route/ShowResponse.php b/src/Model/Route/ShowResponse.php
index 4d7a9d7..9fd0334 100644
--- a/src/Model/Route/ShowResponse.php
+++ b/src/Model/Route/ShowResponse.php
@@ -18,35 +18,21 @@ use Mailgun\Model\ApiResponse;
  */
 final class ShowResponse implements ApiResponse
 {
-    /**
-     * @var Route|null
-     */
     private $route;
 
-    /**
-     * {@inheritdoc}
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        if (isset($data['route'])) {
-            return new self(Route::create($data['route']));
-        }
+        $model = new self();
+        $model->route = isset($data['route']) ? Route::create($data['route']) : null;
 
-        return new self();
+        return $model;
     }
 
-    /**
-     * ShowResponse constructor.
-     */
-    private function __construct(Route $route = null)
+    private function __construct()
     {
-        $this->route = $route;
     }
 
-    /**
-     * @return Route|null
-     */
-    public function getRoute()
+    public function getRoute(): ?Route
     {
         return $this->route;
     }
diff --git a/src/Model/Route/UpdateResponse.php b/src/Model/Route/UpdateResponse.php
index 041a28b..876e42f 100644
--- a/src/Model/Route/UpdateResponse.php
+++ b/src/Model/Route/UpdateResponse.php
@@ -18,48 +18,28 @@ use Mailgun\Model\ApiResponse;
  */
 final class UpdateResponse implements ApiResponse
 {
-    /**
-     * @var string|null
-     */
     private $message;
-
-    /**
-     * @var Route|null
-     */
     private $route;
 
-    /**
-     * @return self
-     */
-    public static function create(array $data)
+    public static function create(array $data): self
     {
-        $message = isset($data['message']) ? $data['message'] : null;
-        $route = isset($data['id']) ? Route::create($data) : null;
+        $model = new self();
+        $model->message = $data['message'] ?? null;
+        $model->route = isset($data['id']) ? Route::create($data) : null;
 
-        return new self($message, $route);
+        return $model;
     }
 
-    /**
-     * @param string|null $message
-     */
-    private function __construct($message = null, Route $route = null)
+    private function __construct()
     {
-        $this->message = $message;
-        $this->route = $route;
     }
 
-    /**
-     * @return string|null
-     */
-    public function getMessage()
+    public function getMessage(): ?string
     {
         return $this->message;
     }
 
-    /**
-     * @return Route|null
-     */
-    public function getRoute()
+    public function getRoute(): ?Route
     {
         return $this->route;
     }