diff --git a/src/Attachment/AttachmentService.php b/src/Attachment/AttachmentService.php
index 32873ff08a48ad1fed60e69080c3fe408bbe56cf..b7504babab4270eede4e944d2c9204b3369e1529 100644
--- a/src/Attachment/AttachmentService.php
+++ b/src/Attachment/AttachmentService.php
@@ -30,7 +30,7 @@ class AttachmentService extends \JiraCloud\JiraClient
      *
      * @return Attachment
      */
-    public function get(int|string $id, string $outDir = null, bool $overwrite = false, int $mode = 0777, bool $recursive = true): Attachment
+    public function get(int|string $id, ?string $outDir = null, bool $overwrite = false, int $mode = 0777, bool $recursive = true): Attachment
     {
         $ret = $this->exec($this->uri.$id, null);
 
diff --git a/src/Auth/AuthService.php b/src/Auth/AuthService.php
index e9deafb1d49027d92c4374e0f33936a3797f2dfb..06490a761c74464302a5166a379f9b80befe7a1d 100644
--- a/src/Auth/AuthService.php
+++ b/src/Auth/AuthService.php
@@ -80,7 +80,7 @@ class AuthService extends \JiraCloud\JiraClient
      * @throws \Exception
      * @throws \JiraCloud\JiraException
      */
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
         $this->setAPIUri($this->auth_api_uri);
diff --git a/src/Epic/EpicService.php b/src/Epic/EpicService.php
index 5c1a83422fdab729910ecb19beef59aafe1f4bfe..b5a3bdc52fd1a00437837abe04be49696f903609 100644
--- a/src/Epic/EpicService.php
+++ b/src/Epic/EpicService.php
@@ -11,7 +11,7 @@ class EpicService extends \JiraCloud\JiraClient
     private $uri = '/epic';
     private $version = '1.0';
 
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
         $this->setAPIUri('/rest/agile/'.$this->version);
diff --git a/src/Issue/AgileIssueService.php b/src/Issue/AgileIssueService.php
index 1de9adaeab27bcc02b2bb8e5ffdf44bc7f6a1822..dc2eefaf0398d9a057a17c8f747e7c208e61be60 100644
--- a/src/Issue/AgileIssueService.php
+++ b/src/Issue/AgileIssueService.php
@@ -9,7 +9,7 @@ class AgileIssueService extends \JiraCloud\JiraClient
 {
     private $uri = '/rest/agile/1.0';
 
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
     }
diff --git a/src/Issue/IssueField.php b/src/Issue/IssueField.php
index cdf3a7160b49262057c81f9538dd8a9611222a9f..0bd2925b488ce394da1f7ae6ce248febfdc95570 100644
--- a/src/Issue/IssueField.php
+++ b/src/Issue/IssueField.php
@@ -61,7 +61,7 @@ class IssueField implements \JsonSerializable
     public ?Reporter $assignee = null;
 
     /** @var \JiraCloud\Issue\Version[]|null */
-    public array|null $versions = null;
+    public ?array $versions = null;
 
     /** @var \JiraCloud\Issue\Attachment[] */
     public $attachment;
diff --git a/src/Issue/IssueService.php b/src/Issue/IssueService.php
index 62f6a86b5a48a1b3569374504b0d991135de2779..d0da5337a473adf11f001dc4b54103655513486c 100644
--- a/src/Issue/IssueService.php
+++ b/src/Issue/IssueService.php
@@ -39,7 +39,7 @@ class IssueService extends \JiraCloud\JiraClient
      *
      * @return Issue class
      */
-    public function get(int|string $issueIdOrKey, array $paramArray = [], Issue $issueObject = null): Issue
+    public function get(int|string $issueIdOrKey, array $paramArray = [], ?Issue $issueObject = null): Issue
     {
         $issueObject = ($issueObject) ? $issueObject : new Issue();
 
diff --git a/src/Issue/Reporter.php b/src/Issue/Reporter.php
index deb4b714bc87053ac85c5daaca6d6745964776c9..1727f2ac75a3e31eb5a4aa72ae43bba18d478dcb 100644
--- a/src/Issue/Reporter.php
+++ b/src/Issue/Reporter.php
@@ -14,7 +14,7 @@ class Reporter implements \JsonSerializable
 
     public ?string $emailAddress = null;
 
-    public array|null $avatarUrls;
+    public ?array $avatarUrls;
 
     public string $displayName;
 
diff --git a/src/JiraClient.php b/src/JiraClient.php
index 7ecd4145cab1001d47d8a2ab8bd59162ced6b4d2..6e9ce020e3b230c9e2deb34d6c7ce5b443f58cbe 100644
--- a/src/JiraClient.php
+++ b/src/JiraClient.php
@@ -59,7 +59,7 @@ class JiraClient
      *
      * @throws JiraException
      */
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, string $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, string $path = './')
     {
         if ($configuration === null) {
             if (!file_exists($path.'.env')) {
@@ -186,7 +186,7 @@ class JiraClient
      *
      * @return string|bool
      */
-    public function exec(string $context, array|string $post_data = null, string $custom_request = null, string $cookieFile = null): string|bool
+    public function exec(string $context, array|string|null $post_data = null, ?string $custom_request = null, ?string $cookieFile = null): string|bool
     {
         $url = $this->createUrlByContext($context);
 
@@ -236,8 +236,8 @@ class JiraClient
             curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
         }
 
-       // See https://github.com/php/php-src/issues/14184
-       // curl_setopt($ch, CURLOPT_ENCODING, '');
+        // See https://github.com/php/php-src/issues/14184
+        // curl_setopt($ch, CURLOPT_ENCODING, '');
 
         curl_setopt(
             $ch,
@@ -405,7 +405,7 @@ class JiraClient
     /**
      * Add authorize to curl request.
      */
-    protected function authorization(\CurlHandle $ch, array &$curl_http_headers, string $cookieFile = null): void
+    protected function authorization(\CurlHandle $ch, array &$curl_http_headers, ?string $cookieFile = null): void
     {
         // use cookie
         if ($this->getConfiguration()->isCookieAuthorizationEnabled()) {
@@ -472,7 +472,7 @@ class JiraClient
     /**
      * download and save into outDir.
      */
-    public function download(string $url, string $outDir, string $file, string $cookieFile = null): mixed
+    public function download(string $url, string $outDir, string $file, ?string $cookieFile = null): mixed
     {
         $curl_http_header = [
             'Accept: */*',
diff --git a/src/JiraException.php b/src/JiraException.php
index ec7aebf939b29f336d4fdb9024dff5366555f809..d69b1ce79db7b72ec752a137d2301d43f7f22b62 100644
--- a/src/JiraException.php
+++ b/src/JiraException.php
@@ -17,7 +17,7 @@ class JiraException extends \Exception
     /**
      * Create a new Jira exception instance.
      */
-    public function __construct(?string $message = null, int $code = 0, \Throwable $previous = null, string $response = null)
+    public function __construct(?string $message = null, int $code = 0, ?\Throwable $previous = null, ?string $response = null)
     {
         parent::__construct($message, $code, $previous);
 
diff --git a/src/RapidCharts/ScopeChangeBurnDownChartService.php b/src/RapidCharts/ScopeChangeBurnDownChartService.php
index 7700a4ff047e0011d529f20a8ccd08f07bab8579..6a68b35446ca1c790769dc05c88e6ebe6e4d7704 100644
--- a/src/RapidCharts/ScopeChangeBurnDownChartService.php
+++ b/src/RapidCharts/ScopeChangeBurnDownChartService.php
@@ -12,7 +12,7 @@ class ScopeChangeBurnDownChartService extends \JiraCloud\JiraClient
 
     private $uri = '/rapid/charts/scopechangeburndownchart';
 
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
         $this->setupAPIUri();
diff --git a/src/Request/RequestService.php b/src/Request/RequestService.php
index f346bf895c1ed156874f7144b93f08de25cfb2fe..9e87f925a01d2c5e58ec032e0f1796e3c998421b 100644
--- a/src/Request/RequestService.php
+++ b/src/Request/RequestService.php
@@ -23,7 +23,7 @@ class RequestService extends \JiraCloud\JiraClient
      * @throws JiraException
      * @throws \Exception
      */
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
         $this->setupAPIUri();
diff --git a/src/ServiceDesk/Request/RequestService.php b/src/ServiceDesk/Request/RequestService.php
index 007e445a2621f3b30c46ba3f4b9ee338390623e4..906498dc044095e49df112bcc81973ff4dc3b37c 100644
--- a/src/ServiceDesk/Request/RequestService.php
+++ b/src/ServiceDesk/Request/RequestService.php
@@ -65,7 +65,7 @@ class RequestService
      *
      * @see https://docs.atlassian.com/jira-servicedesk/REST/3.6.2/#servicedeskapi/request-getCustomerRequestByIdOrKey
      */
-    public function get(string $issueId, array $expandParameters = [], Request $request = null): Request
+    public function get(string $issueId, array $expandParameters = [], ?Request $request = null): Request
     {
         $request = ($request) ?: new Request();
 
@@ -88,7 +88,7 @@ class RequestService
      *
      * @see https://docs.atlassian.com/jira-servicedesk/REST/3.6.2/#servicedeskapi/request-getMyCustomerRequests
      */
-    public function getRequestsByCustomer(Customer $customer, array $searchParameters, int $serviceDeskId = null): array
+    public function getRequestsByCustomer(Customer $customer, array $searchParameters, ?int $serviceDeskId = null): array
     {
         $defaultSearchParameters = [
             'requestOwnership' => 'OWNED_REQUESTS',
diff --git a/src/ServiceDesk/ServiceDeskClient.php b/src/ServiceDesk/ServiceDeskClient.php
index 0ed2aa32a0ecb23d6c003ce32fa7003d677a535e..9cabdbb73a1fdaca9702ed27e73211611dd17055 100644
--- a/src/ServiceDesk/ServiceDeskClient.php
+++ b/src/ServiceDesk/ServiceDeskClient.php
@@ -12,8 +12,8 @@ use Psr\Log\LoggerInterface;
 class ServiceDeskClient extends JiraClient
 {
     public function __construct(
-        ConfigurationInterface $configuration = null,
-        LoggerInterface $logger = null,
+        ?ConfigurationInterface $configuration = null,
+        ?LoggerInterface $logger = null,
         string $path = './'
     ) {
         parent::__construct($configuration, $logger, $path);
diff --git a/src/Sprint/SprintSearchResult.php b/src/Sprint/SprintSearchResult.php
index 69805ef7fea80fe24458a23184cda2a0eea52d92..13635886143f56084532a75086855e853be0bd55 100644
--- a/src/Sprint/SprintSearchResult.php
+++ b/src/Sprint/SprintSearchResult.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * Created by PhpStorm.
  * User: keanor
diff --git a/src/Sprint/SprintService.php b/src/Sprint/SprintService.php
index 27941f94ef30620407b79b625c0758af1c90b1a7..474aae2889e2f4de50c89d2c19e58068c216bdb4 100644
--- a/src/Sprint/SprintService.php
+++ b/src/Sprint/SprintService.php
@@ -14,7 +14,7 @@ class SprintService extends JiraClient
 {
     private $uri = '/sprint';
 
-    public function __construct(ConfigurationInterface $configuration = null, LoggerInterface $logger = null, $path = './')
+    public function __construct(?ConfigurationInterface $configuration = null, ?LoggerInterface $logger = null, $path = './')
     {
         parent::__construct($configuration, $logger, $path);
         $this->setAPIUri('/rest/agile/1.0');