diff --git a/composer.json b/composer.json
index a12ee58..05f7f3a 100644
--- a/composer.json
+++ b/composer.json
@@ -36,7 +36,7 @@
         "docs": "https://github.com/cybercog/youtrack-rest-php/wiki"
     },
     "require": {
-        "php": "^8.0",
+        "php": "^8.1",
         "ext-json": "*",
         "guzzlehttp/guzzle": "^6.2"
     },
diff --git a/contracts/Authenticator/Authenticator.php b/contracts/Authenticator/Authenticator.php
index 662836c..b8cd702 100644
--- a/contracts/Authenticator/Authenticator.php
+++ b/contracts/Authenticator/Authenticator.php
@@ -20,17 +20,12 @@ interface Authenticator
     /**
      * Authenticate API Client.
      *
-     * @param \Cog\Contracts\YouTrack\Rest\Client\Client $client
-     * @return void
-     *
      * @throws \Cog\Contracts\YouTrack\Rest\Authenticator\Exceptions\AuthenticationException
      */
     public function authenticate(ClientInterface $client): void;
 
     /**
      * Retrieve authentication token.
-     *
-     * @return string
      */
     public function token(): string;
 }
diff --git a/contracts/Authorizer/Authorizer.php b/contracts/Authorizer/Authorizer.php
index e64c720..5fb8207 100644
--- a/contracts/Authorizer/Authorizer.php
+++ b/contracts/Authorizer/Authorizer.php
@@ -19,9 +19,6 @@ interface Authorizer
 {
     /**
      * Append authorization headers to REST client.
-     *
-     * @param \Cog\Contracts\YouTrack\Rest\Client\Client $client
-     * @return void
      */
     public function appendHeadersTo(ClientInterface $client): void;
 }
diff --git a/contracts/Client/Client.php b/contracts/Client/Client.php
index 5cd576b..358777f 100644
--- a/contracts/Client/Client.php
+++ b/contracts/Client/Client.php
@@ -95,10 +95,6 @@ public function delete(string $uri, array $params = [], array $options = []): Re
 
     /**
      * Write header value.
-     *
-     * @param string $key
-     * @param string $value
-     * @return void
      */
     public function withHeader(string $key, string $value): void;
 
diff --git a/contracts/Response/Response.php b/contracts/Response/Response.php
index f54e85b..f330ea0 100644
--- a/contracts/Response/Response.php
+++ b/contracts/Response/Response.php
@@ -19,8 +19,6 @@ interface Response
 {
     /**
      * Returns original HTTP client response.
-     *
-     * @return \Psr\Http\Message\ResponseInterface
      */
     public function httpResponse(): PsrResponseInterface;
 
@@ -29,37 +27,26 @@ public function httpResponse(): PsrResponseInterface;
      *
      * The status code is a 3-digit integer result code of the server's attempt
      * to understand and satisfy the request.
-     *
-     * @return int
      */
     public function statusCode(): int;
 
     /**
      * Retrieves a comma-separated string of the values for a single header.
-     *
-     * @param string $header
-     * @return string
      */
     public function header(string $header): string;
 
     /**
      * Transform response cookie headers to string.
-     *
-     * @return string
      */
     public function cookie(): string;
 
     /**
      * Returns response location header.
-     *
-     * @return string
      */
     public function location(): string;
 
     /**
      * Returns body of the response.
-     *
-     * @return string
      */
     public function body(): string;
 
@@ -72,37 +59,26 @@ public function toArray(): array;
 
     /**
      * Assert the status code of the response.
-     *
-     * @param int $code
-     * @return bool
      */
     public function isStatusCode(int $code): bool;
 
     /**
      * Determine if response has successful status code.
-     *
-     * @return bool
      */
     public function isSuccess(): bool;
 
     /**
      * Determine if response has redirect status code.
-     *
-     * @return bool
      */
     public function isRedirect(): bool;
 
     /**
      * Determine if response has client error status code.
-     *
-     * @return bool
      */
     public function isClientError(): bool;
 
     /**
      * Determine if response has server error status code.
-     *
-     * @return bool
      */
     public function isServerError(): bool;
 }
diff --git a/src/Authenticator/CookieAuthenticator.php b/src/Authenticator/CookieAuthenticator.php
index a5b4b4d..3dd5d82 100644
--- a/src/Authenticator/CookieAuthenticator.php
+++ b/src/Authenticator/CookieAuthenticator.php
@@ -19,46 +19,22 @@
 class CookieAuthenticator implements
     AuthenticatorInterface
 {
-    /**
-     * @var string
-     */
-    private $username = '';
-
-    /**
-     * @var string
-     */
-    private $password = '';
-
-    /**
-     * @var string
-     */
-    private $cookie = '';
-
     /**
      * Determine is trying to authenticate.
-     *
-     * @var bool
      */
-    private $isAuthenticating = false;
+    private bool $isAuthenticating = false;
 
-    /**
-     * CookieAuthenticator constructor.
-     *
-     * @param string $username
-     * @param string $password
-     */
-    public function __construct(string $username, string $password)
-    {
-        $this->username = $username;
-        $this->password = $password;
+    private string $cookie = '';
+
+    public function __construct(
+        private string $username,
+        private string $password,
+    ) {
     }
 
     /**
      * Authenticate client and returns cookie on success login.
      *
-     * @param \Cog\Contracts\YouTrack\Rest\Client\Client $client
-     * @return void
-     *
      * @throws \Cog\Contracts\YouTrack\Rest\Authenticator\Exceptions\AuthenticationException
      */
     public function authenticate(ClientInterface $client): void
@@ -81,8 +57,6 @@ public function authenticate(ClientInterface $client): void
 
     /**
      * Retrieve authentication token.
-     *
-     * @return string
      */
     public function token(): string
     {
diff --git a/src/Authorizer/CookieAuthorizer.php b/src/Authorizer/CookieAuthorizer.php
index c91247b..0deb55e 100644
--- a/src/Authorizer/CookieAuthorizer.php
+++ b/src/Authorizer/CookieAuthorizer.php
@@ -20,27 +20,14 @@
 class CookieAuthorizer implements
     AuthorizerInterface
 {
-    /**
-     * @var \Cog\Contracts\YouTrack\Rest\Authenticator\Authenticator
-     */
-    private $authenticator;
-
-    /**
-     * CookieAuthorizer constructor.
-     *
-     * @param \Cog\Contracts\YouTrack\Rest\Authenticator\Authenticator $authenticator
-     */
-    public function __construct(AuthenticatorInterface $authenticator)
-    {
-        $this->authenticator = $authenticator;
+    public function __construct(
+        private AuthenticatorInterface $authenticator,
+    ) {
     }
 
     /**
      * Append authorization headers to REST client.
      *
-     * @param \Cog\Contracts\YouTrack\Rest\Client\Client $client
-     * @return void
-     *
      * @throws \Cog\Contracts\YouTrack\Rest\Authenticator\Exceptions\AuthenticationException
      */
     public function appendHeadersTo(ClientInterface $client): void
diff --git a/src/Authorizer/TokenAuthorizer.php b/src/Authorizer/TokenAuthorizer.php
index 5c5f1c1..d79daef 100644
--- a/src/Authorizer/TokenAuthorizer.php
+++ b/src/Authorizer/TokenAuthorizer.php
@@ -22,26 +22,13 @@
 class TokenAuthorizer implements
     AuthorizerInterface
 {
-    /**
-     * @var string
-     */
-    private $token;
-
-    /**
-     * TokenAuthorizer constructor.
-     *
-     * @param string $token
-     */
-    public function __construct(string $token)
-    {
-        $this->token = $token;
+    public function __construct(
+        private string $token,
+    ) {
     }
 
     /**
      * Append authorization headers to REST client.
-     *
-     * @param \Cog\Contracts\YouTrack\Rest\Client\Client $client
-     * @return void
      */
     public function appendHeadersTo(ClientInterface $client): void
     {
diff --git a/src/Client/YouTrackClient.php b/src/Client/YouTrackClient.php
index 6f8003b..e606381 100644
--- a/src/Client/YouTrackClient.php
+++ b/src/Client/YouTrackClient.php
@@ -29,48 +29,29 @@
 class YouTrackClient implements
     RestClientInterface
 {
-    /**
-     * HTTP Client.
-     *
-     * @var \Cog\Contracts\YouTrack\Rest\HttpClient\HttpClient
-     */
-    private $httpClient;
-
-    /**
-     * Authorization driver.
-     *
-     * @var \Cog\Contracts\YouTrack\Rest\Authorizer\Authorizer
-     */
-    private $authorizer;
-
     /**
      * Endpoint path prefix.
      *
      * @todo test it
-     *
-     * @var string
      */
-    private $endpointPathPrefix;
+    private string $endpointPathPrefix;
 
     /**
      * Request headers.
      *
      * @var array
      */
-    private $headers = [];
-
-    /**
-     * YouTrackClient constructor.
-     *
-     * @param \Cog\Contracts\YouTrack\Rest\HttpClient\HttpClient $httpClient
-     * @param \Cog\Contracts\YouTrack\Rest\Authorizer\Authorizer $authorizer
-     * @param string $endpointPathPrefix
-     */
-    public function __construct(HttpClientInterface $httpClient, AuthorizerInterface $authorizer, string $endpointPathPrefix = null)
-    {
-        $this->httpClient = $httpClient;
-        $this->authorizer = $authorizer;
-        $this->endpointPathPrefix = $endpointPathPrefix !== null ? $endpointPathPrefix : 'api';
+    private array $headers = [];
+
+    public function __construct(
+        private HttpClientInterface $httpClient,
+        private AuthorizerInterface $authorizer,
+        // @todo test it
+        string | null $endpointPathPrefix = null,
+    ) {
+        $this->endpointPathPrefix = $endpointPathPrefix !== null
+            ? $endpointPathPrefix
+            : 'api';
     }
 
     /**
@@ -89,7 +70,11 @@ public function __construct(HttpClientInterface $httpClient, AuthorizerInterface
     public function request(string $method, string $uri, array $params = [], array $options = []): ResponseInterface
     {
         try {
-            $response = $this->httpClient->request($method, $this->buildUri($uri), $this->buildOptions($params, $options));
+            $response = $this->httpClient->request(
+                $method,
+                $this->buildUri($uri),
+                $this->buildOptions($params, $options),
+            );
         } catch (HttpClientException $e) {
             switch ($e->getCode()) {
                 case 401:
@@ -174,10 +159,6 @@ public function delete(string $uri, array $params = [], array $options = []): Re
 
     /**
      * Write header value.
-     *
-     * @param string $key
-     * @param string $value
-     * @return void
      */
     public function withHeader(string $key, string $value): void
     {
@@ -197,9 +178,6 @@ public function withHeaders(array $headers): void
 
     /**
      * Build endpoint URI.
-     *
-     * @param string $uri
-     * @return string
      */
     protected function buildUri(string $uri): string
     {
diff --git a/src/HttpClient/GuzzleHttpClient.php b/src/HttpClient/GuzzleHttpClient.php
index 023cd28..6f9c0a6 100644
--- a/src/HttpClient/GuzzleHttpClient.php
+++ b/src/HttpClient/GuzzleHttpClient.php
@@ -25,21 +25,9 @@
 class GuzzleHttpClient implements
     HttpClientInterface
 {
-    /**
-     * GuzzleHttp client.
-     *
-     * @var \GuzzleHttp\ClientInterface
-     */
-    protected $httpClient;
-
-    /**
-     * Create a new GuzzleHttpClient instance.
-     *
-     * @param \GuzzleHttp\ClientInterface $httpClient
-     */
-    public function __construct(ClientInterface $httpClient)
-    {
-        $this->httpClient = $httpClient;
+    public function __construct(
+        private ClientInterface $httpClient,
+    ) {
     }
 
     /**
diff --git a/src/Response/YouTrackResponse.php b/src/Response/YouTrackResponse.php
index b3aa6b0..90b8a4e 100644
--- a/src/Response/YouTrackResponse.php
+++ b/src/Response/YouTrackResponse.php
@@ -19,27 +19,13 @@
 class YouTrackResponse implements
     ResponseInterface
 {
-    /**
-     * Original HTTP client response.
-     *
-     * @var \Psr\Http\Message\ResponseInterface
-     */
-    private $response;
-
-    /**
-     * YouTrackResponse constructor.
-     *
-     * @param \Psr\Http\Message\ResponseInterface $response
-     */
-    public function __construct(PsrResponseInterface $response)
-    {
-        $this->response = $response;
+    public function __construct(
+        private PsrResponseInterface $response,
+    ) {
     }
 
     /**
      * Returns original HTTP client response.
-     *
-     * @return \Psr\Http\Message\ResponseInterface
      */
     public function httpResponse(): PsrResponseInterface
     {
@@ -51,8 +37,6 @@ public function httpResponse(): PsrResponseInterface
      *
      * The status code is a 3-digit integer result code of the server's attempt
      * to understand and satisfy the request.
-     *
-     * @return int
      */
     public function statusCode(): int
     {
@@ -61,9 +45,6 @@ public function statusCode(): int
 
     /**
      * Retrieves a comma-separated string of the values for a single header.
-     *
-     * @param string $header
-     * @return string
      */
     public function header(string $header): string
     {
@@ -72,8 +53,6 @@ public function header(string $header): string
 
     /**
      * Transform response cookie headers to string.
-     *
-     * @return string
      */
     public function cookie(): string
     {
@@ -82,8 +61,6 @@ public function cookie(): string
 
     /**
      * Returns response location header.
-     *
-     * @return string
      */
     public function location(): string
     {
@@ -92,12 +69,10 @@ public function location(): string
 
     /**
      * Returns body of the response.
-     *
-     * @return string
      */
     public function body(): string
     {
-        return (string) $this->response->getBody();
+        return (string)$this->response->getBody();
     }
 
     /**
@@ -112,9 +87,6 @@ public function toArray(): array
 
     /**
      * Assert the status code of the response.
-     *
-     * @param int $code
-     * @return bool
      */
     public function isStatusCode(int $code): bool
     {
@@ -123,8 +95,6 @@ public function isStatusCode(int $code): bool
 
     /**
      * Determine if response has successful status code.
-     *
-     * @return bool
      */
     public function isSuccess(): bool
     {
@@ -133,8 +103,6 @@ public function isSuccess(): bool
 
     /**
      * Determine if response has redirect status code.
-     *
-     * @return bool
      */
     public function isRedirect(): bool
     {
@@ -143,8 +111,6 @@ public function isRedirect(): bool
 
     /**
      * Determine if response has client error status code.
-     *
-     * @return bool
      */
     public function isClientError(): bool
     {
@@ -153,8 +119,6 @@ public function isClientError(): bool
 
     /**
      * Determine if response has server error status code.
-     *
-     * @return bool
      */
     public function isServerError(): bool
     {