* Fix Psalm errors

Author: sveldhuisen

src/Exception/OAuthException.php

@@ -9,6 +9,6 @@
 /**
  * Represents errors during OAuth protocol.
  */
-class OAuthException extends RuntimeException implements OAuthExceptionInterface
+final class OAuthException extends RuntimeException implements OAuthExceptionInterface
 {
 }

src/GrantType/AuthorizationCodeGrantType.php

@@ -10,7 +10,7 @@
 /**
  * Implementation of the OAuth authorization grant type.
  */
-class AuthorizationCodeGrantType implements RefreshableGrantTypeInterface
+final class AuthorizationCodeGrantType implements RefreshableGrantTypeInterface
 {
     use TokensExtractor;
 
@@ -50,6 +50,7 @@ public function __construct(
      *
      * @throws TransportExceptionInterface
      */
+    #[\Override]
     public function getTokens(): Tokens
     {
         $response = $this->client->request('POST', $this->tokenUrl, [
@@ -64,6 +65,7 @@ public function getTokens(): Tokens
         return $this->extractTokens($response);
     }
 
+    #[\Override]
     public function getRefreshTokenGrant(string $refreshToken): GrantTypeInterface
     {
         return new RefreshTokenGrantType($this->client, $this->tokenUrl, $refreshToken, $this->clientId, $this->clientSecret);

src/GrantType/ClientCredentialsGrantType.php

@@ -10,7 +10,7 @@
 /**
  * Implementation of the OAuth client credentials grant type.
  */
-class ClientCredentialsGrantType implements GrantTypeInterface
+final class ClientCredentialsGrantType implements GrantTypeInterface
 {
     use TokensExtractor;
 
@@ -45,6 +45,7 @@ public function __construct(
      *
      * @throws TransportExceptionInterface
      */
+    #[\Override]
     public function getTokens(): Tokens
     {
         $response = $this->client->request('POST', $this->tokenUrl, [

src/GrantType/PasswordGrantType.php

@@ -10,7 +10,7 @@
 /**
  * Implementation of the OAuth password grant type.
  */
-class PasswordGrantType implements GrantTypeInterface
+final class PasswordGrantType implements GrantTypeInterface
 {
     use TokensExtractor;