Fix ArrayAccess and JsonSerializable return types

First round of modifications for PHP 8.1

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

34 files changed, 79 insertions, 74 deletions

diff --git a/apps/files_external/lib/Lib/Auth/AuthMechanism.php b/apps/files_external/lib/Lib/Auth/AuthMechanism.php
index f676957794d..210dd705723 100644
--- a/apps/files_external/lib/Lib/Auth/AuthMechanism.php
+++ b/apps/files_external/lib/Lib/Auth/AuthMechanism.php
@@ -90,10 +90,8 @@ class AuthMechanism implements \JsonSerializable {
 
 	/**
 	 * Serialize into JSON for client-side JS
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		$data = $this->jsonSerializeDefinition();
 		$data += $this->jsonSerializeIdentifier();
 
diff --git a/apps/files_external/lib/Lib/Backend/Backend.php b/apps/files_external/lib/Lib/Backend/Backend.php
index a6e63eb30d1..021d208aed3 100644
--- a/apps/files_external/lib/Lib/Backend/Backend.php
+++ b/apps/files_external/lib/Lib/Backend/Backend.php
@@ -137,10 +137,8 @@ class Backend implements \JsonSerializable {
 
 	/**
 	 * Serialize into JSON for client-side JS
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		$data = $this->jsonSerializeDefinition();
 		$data += $this->jsonSerializeIdentifier();
 
diff --git a/apps/files_external/lib/Lib/DefinitionParameter.php b/apps/files_external/lib/Lib/DefinitionParameter.php
index fbfbbfd4686..6b081d5a089 100644
--- a/apps/files_external/lib/Lib/DefinitionParameter.php
+++ b/apps/files_external/lib/Lib/DefinitionParameter.php
@@ -167,10 +167,8 @@ class DefinitionParameter implements \JsonSerializable {
 
 	/**
 	 * Serialize into JSON for client-side JS
-	 *
-	 * @return string
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'value' => $this->getText(),
 			'flags' => $this->getFlags(),
diff --git a/apps/files_external/lib/Lib/StorageConfig.php b/apps/files_external/lib/Lib/StorageConfig.php
index 97b72005018..26ba483b00e 100644
--- a/apps/files_external/lib/Lib/StorageConfig.php
+++ b/apps/files_external/lib/Lib/StorageConfig.php
@@ -396,10 +396,8 @@ class StorageConfig implements \JsonSerializable {
 
 	/**
 	 * Serialize config to JSON
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		$result = [];
 		if (!is_null($this->id)) {
 			$result['id'] = $this->id;
diff --git a/apps/theming/lib/Service/JSDataService.php b/apps/theming/lib/Service/JSDataService.php
index a6e5d6f8e36..1c4d138a764 100644
--- a/apps/theming/lib/Service/JSDataService.php
+++ b/apps/theming/lib/Service/JSDataService.php
@@ -50,7 +50,7 @@ class JSDataService implements \JsonSerializable {
 		$this->appConfig = $appConfig;
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'name' => $this->themingDefaults->getName(),
 			'url' => $this->themingDefaults->getBaseUrl(),
diff --git a/apps/user_status/lib/Service/JSDataService.php b/apps/user_status/lib/Service/JSDataService.php
index 6d83591ab2f..c08643ec64f 100644
--- a/apps/user_status/lib/Service/JSDataService.php
+++ b/apps/user_status/lib/Service/JSDataService.php
@@ -49,7 +49,7 @@ class JSDataService implements \JsonSerializable {
 		$this->statusService = $statusService;
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		$user = $this->userSession->getUser();
 
 		if ($user === null) {
diff --git a/core/Command/Broadcast/Test.php b/core/Command/Broadcast/Test.php
index 91050725e17..86cd30e4b4c 100644
--- a/core/Command/Broadcast/Test.php
+++ b/core/Command/Broadcast/Test.php
@@ -87,7 +87,7 @@ class Test extends Command {
 				];
 			}
 
-			public function jsonSerialize() {
+			public function jsonSerialize(): array {
 				return [
 					'description' => 'this is a test event',
 				];
diff --git a/lib/private/Accounts/Account.php b/lib/private/Accounts/Account.php
index 1e4189f2b35..540d15cd4b9 100644
--- a/lib/private/Accounts/Account.php
+++ b/lib/private/Accounts/Account.php
@@ -104,7 +104,8 @@ class Account implements IAccount {
 		return $result;
 	}
 
-	public function jsonSerialize() {
+	/** @return IAccountPropertyCollection[]|IAccountProperty[] */
+	public function jsonSerialize(): array {
 		return $this->properties;
 	}
 
diff --git a/lib/private/Accounts/AccountProperty.php b/lib/private/Accounts/AccountProperty.php
index 0e6356e9e92..4b7f2b0c04c 100644
--- a/lib/private/Accounts/AccountProperty.php
+++ b/lib/private/Accounts/AccountProperty.php
@@ -54,7 +54,7 @@ class AccountProperty implements IAccountProperty {
 		$this->verificationData = $verificationData;
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'name' => $this->getName(),
 			'value' => $this->getValue(),
diff --git a/lib/private/Accounts/AccountPropertyCollection.php b/lib/private/Accounts/AccountPropertyCollection.php
index 3aed76d8746..091c5734218 100644
--- a/lib/private/Accounts/AccountPropertyCollection.php
+++ b/lib/private/Accounts/AccountPropertyCollection.php
@@ -102,7 +102,7 @@ class AccountPropertyCollection implements IAccountPropertyCollection {
 		return $this;
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [$this->collectionName => $this->properties];
 	}
 
diff --git a/lib/private/AppFramework/Http/Request.php b/lib/private/AppFramework/Http/Request.php
index a95fd208155..c67500bcaa4 100644
--- a/lib/private/AppFramework/Http/Request.php
+++ b/lib/private/AppFramework/Http/Request.php
@@ -199,6 +199,7 @@ class Request implements \ArrayAccess, \Countable, IRequest {
 	 * @param string $offset
 	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		return isset($this->items['parameters'][$offset])
 			? $this->items['parameters'][$offset]
@@ -210,7 +211,7 @@ class Request implements \ArrayAccess, \Countable, IRequest {
 	 * @param string $offset
 	 * @param mixed $value
 	 */
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		throw new \RuntimeException('You cannot change the contents of the request object');
 	}
 
@@ -218,7 +219,7 @@ class Request implements \ArrayAccess, \Countable, IRequest {
 	 * @see offsetExists
 	 * @param string $offset
 	 */
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		throw new \RuntimeException('You cannot change the contents of the request object');
 	}
 
diff --git a/lib/private/AppFramework/Utility/SimpleContainer.php b/lib/private/AppFramework/Utility/SimpleContainer.php
index c38dbadf0a9..598c66b6aba 100644
--- a/lib/private/AppFramework/Utility/SimpleContainer.php
+++ b/lib/private/AppFramework/Utility/SimpleContainer.php
@@ -197,13 +197,15 @@ class SimpleContainer implements ArrayAccess, ContainerInterface, IContainer {
 	/**
 	 * @deprecated 20.0.0 use \Psr\Container\ContainerInterface::has
 	 */
-	public function offsetExists($id) {
+	public function offsetExists($id): bool {
 		return $this->container->offsetExists($id);
 	}
 
 	/**
 	 * @deprecated 20.0.0 use \Psr\Container\ContainerInterface::get
+	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($id) {
 		return $this->container->offsetGet($id);
 	}
@@ -211,14 +213,14 @@ class SimpleContainer implements ArrayAccess, ContainerInterface, IContainer {
 	/**
 	 * @deprecated 20.0.0 use \OCP\IContainer::registerService
 	 */
-	public function offsetSet($id, $service) {
+	public function offsetSet($id, $service): void {
 		$this->container->offsetSet($id, $service);
 	}
 
 	/**
 	 * @deprecated 20.0.0
 	 */
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		$this->container->offsetUnset($offset);
 	}
 }
diff --git a/lib/private/Authentication/Token/DefaultToken.php b/lib/private/Authentication/Token/DefaultToken.php
index 5a008586a90..b649fdbb6af 100644
--- a/lib/private/Authentication/Token/DefaultToken.php
+++ b/lib/private/Authentication/Token/DefaultToken.php
@@ -121,7 +121,7 @@ class DefaultToken extends Entity implements INamedToken {
 		return parent::getPassword();
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'id' => $this->id,
 			'name' => $this->name,
diff --git a/lib/private/Authentication/Token/PublicKeyToken.php b/lib/private/Authentication/Token/PublicKeyToken.php
index 3351c767ce3..d060fe14103 100644
--- a/lib/private/Authentication/Token/PublicKeyToken.php
+++ b/lib/private/Authentication/Token/PublicKeyToken.php
@@ -138,7 +138,7 @@ class PublicKeyToken extends Entity implements INamedToken, IWipeableToken {
 		return parent::getPassword();
 	}
 
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'id' => $this->id,
 			'name' => $this->name,
diff --git a/lib/private/Cache/CappedMemoryCache.php b/lib/private/Cache/CappedMemoryCache.php
index 408c3935ffb..584a53f0ff2 100644
--- a/lib/private/Cache/CappedMemoryCache.php
+++ b/lib/private/Cache/CappedMemoryCache.php
@@ -63,19 +63,23 @@ class CappedMemoryCache implements ICache, \ArrayAccess {
 		return true;
 	}
 
-	public function offsetExists($offset) {
+	public function offsetExists($offset): bool {
 		return $this->hasKey($offset);
 	}
 
+	/**
+	 * @return mixed
+	 */
+	#[\ReturnTypeWillChange]
 	public function &offsetGet($offset) {
 		return $this->cache[$offset];
 	}
 
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->set($offset, $value);
 	}
 
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		$this->remove($offset);
 	}
 
diff --git a/lib/private/Contacts/ContactsMenu/Actions/LinkAction.php b/lib/private/Contacts/ContactsMenu/Actions/LinkAction.php
index 5acafed2fda..3f917854aac 100644
--- a/lib/private/Contacts/ContactsMenu/Actions/LinkAction.php
+++ b/lib/private/Contacts/ContactsMenu/Actions/LinkAction.php
@@ -106,10 +106,7 @@ class LinkAction implements ILinkAction {
 		return $this->appId;
 	}
 
-	/**
-	 * @return array
-	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'title' => $this->name,
 			'icon' => $this->icon,
diff --git a/lib/private/EventDispatcher/GenericEventWrapper.php b/lib/private/EventDispatcher/GenericEventWrapper.php
index 55e23d2ff7f..3574bc8bb83 100644
--- a/lib/private/EventDispatcher/GenericEventWrapper.php
+++ b/lib/private/EventDispatcher/GenericEventWrapper.php
@@ -100,19 +100,23 @@ class GenericEventWrapper extends GenericEvent {
 		return $this->event->hasArgument($key);
 	}
 
+	/**
+	 * @return mixed
+	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($key) {
 		return $this->event->offsetGet($key);
 	}
 
-	public function offsetSet($key, $value) {
-		return $this->event->offsetSet($key, $value);
+	public function offsetSet($key, $value): void {
+		$this->event->offsetSet($key, $value);
 	}
 
-	public function offsetUnset($key) {
-		return $this->event->offsetUnset($key);
+	public function offsetUnset($key): void {
+		$this->event->offsetUnset($key);
 	}
 
-	public function offsetExists($key) {
+	public function offsetExists($key): bool {
 		return $this->event->offsetExists($key);
 	}
 
diff --git a/lib/private/Files/Cache/CacheEntry.php b/lib/private/Files/Cache/CacheEntry.php
index 156f075c2d0..12f0273fb6e 100644
--- a/lib/private/Files/Cache/CacheEntry.php
+++ b/lib/private/Files/Cache/CacheEntry.php
@@ -37,18 +37,22 @@ class CacheEntry implements ICacheEntry {
 		$this->data = $data;
 	}
 
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->data[$offset] = $value;
 	}
 
-	public function offsetExists($offset) {
+	public function offsetExists($offset): bool {
 		return isset($this->data[$offset]);
 	}
 
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		unset($this->data[$offset]);
 	}
 
+	/**
+	 * @return mixed
+	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		if (isset($this->data[$offset])) {
 			return $this->data[$offset];
diff --git a/lib/private/Files/FileInfo.php b/lib/private/Files/FileInfo.php
index 8a8de6e4c19..2f361fc051d 100644
--- a/lib/private/Files/FileInfo.php
+++ b/lib/private/Files/FileInfo.php
@@ -104,18 +104,22 @@ class FileInfo implements \OCP\Files\FileInfo, \ArrayAccess {
 		$this->rawSize = $this->data['size'] ?? 0;
 	}
 
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->data[$offset] = $value;
 	}
 
-	public function offsetExists($offset) {
+	public function offsetExists($offset): bool {
 		return isset($this->data[$offset]);
 	}
 
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		unset($this->data[$offset]);
 	}
 
+	/**
+	 * @return mixed
+	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		if ($offset === 'type') {
 			return $this->getType();
diff --git a/lib/private/FullTextSearch/Model/IndexDocument.php b/lib/private/FullTextSearch/Model/IndexDocument.php
index a1648ab6e2a..3078f12c465 100644
--- a/lib/private/FullTextSearch/Model/IndexDocument.php
+++ b/lib/private/FullTextSearch/Model/IndexDocument.php
@@ -963,10 +963,8 @@ class IndexDocument implements IIndexDocument, JsonSerializable {
 
 	/**
 	 * @since 15.0.0
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'id' => $this->getId(),
 			'providerId' => $this->getProviderId(),
diff --git a/lib/private/FullTextSearch/Model/SearchRequestSimpleQuery.php b/lib/private/FullTextSearch/Model/SearchRequestSimpleQuery.php
index 9c9ac71efa9..d6bfe6d9102 100644
--- a/lib/private/FullTextSearch/Model/SearchRequestSimpleQuery.php
+++ b/lib/private/FullTextSearch/Model/SearchRequestSimpleQuery.php
@@ -168,10 +168,9 @@ final class SearchRequestSimpleQuery implements ISearchRequestSimpleQuery, JsonS
 
 
 	/**
-	 * @return array|mixed
 	 * @since 17.0.0
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'type' => $this->getType(),
 			'field' => $this->getField(),
diff --git a/lib/private/L10N/L10NString.php b/lib/private/L10N/L10NString.php
index 33ccc4b1409..de4bc38d744 100644
--- a/lib/private/L10N/L10NString.php
+++ b/lib/private/L10N/L10NString.php
@@ -82,11 +82,7 @@ class L10NString implements \JsonSerializable {
 		return vsprintf($text, $this->parameters);
 	}
 
-
-	/**
-	 * @return string
-	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): string {
 		return $this->__toString();
 	}
 }
diff --git a/lib/private/Memcache/Cache.php b/lib/private/Memcache/Cache.php
index 95213c16849..1d54a705098 100644
--- a/lib/private/Memcache/Cache.php
+++ b/lib/private/Memcache/Cache.php
@@ -78,19 +78,23 @@ abstract class Cache implements \ArrayAccess, \OCP\ICache {
 
 	//implement the ArrayAccess interface
 
-	public function offsetExists($offset) {
+	public function offsetExists($offset): bool {
 		return $this->hasKey($offset);
 	}
 
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->set($offset, $value);
 	}
 
+	/**
+	 * @return mixed
+	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		return $this->get($offset);
 	}
 
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		$this->remove($offset);
 	}
 }
diff --git a/lib/private/Session/CryptoSessionData.php b/lib/private/Session/CryptoSessionData.php
index 94ad8f90dcf..2e3bd46da5b 100644
--- a/lib/private/Session/CryptoSessionData.php
+++ b/lib/private/Session/CryptoSessionData.php
@@ -195,6 +195,7 @@ class CryptoSessionData implements \ArrayAccess, ISession {
 	 * @param mixed $offset
 	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		return $this->get($offset);
 	}
@@ -203,14 +204,14 @@ class CryptoSessionData implements \ArrayAccess, ISession {
 	 * @param mixed $offset
 	 * @param mixed $value
 	 */
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->set($offset, $value);
 	}
 
 	/**
 	 * @param mixed $offset
 	 */
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		$this->remove($offset);
 	}
 }
diff --git a/lib/private/Session/Session.php b/lib/private/Session/Session.php
index b9497983fbb..affba322bec 100644
--- a/lib/private/Session/Session.php
+++ b/lib/private/Session/Session.php
@@ -55,6 +55,7 @@ abstract class Session implements \ArrayAccess, ISession {
 	 * @param mixed $offset
 	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		return $this->get($offset);
 	}
@@ -63,14 +64,14 @@ abstract class Session implements \ArrayAccess, ISession {
 	 * @param mixed $offset
 	 * @param mixed $value
 	 */
-	public function offsetSet($offset, $value) {
+	public function offsetSet($offset, $value): void {
 		$this->set($offset, $value);
 	}
 
 	/**
 	 * @param mixed $offset
 	 */
-	public function offsetUnset($offset) {
+	public function offsetUnset($offset): void {
 		$this->remove($offset);
 	}
 
diff --git a/lib/public/AppFramework/Services/InitialStateProvider.php b/lib/public/AppFramework/Services/InitialStateProvider.php
index c317fad3f5d..dbc48653792 100644
--- a/lib/public/AppFramework/Services/InitialStateProvider.php
+++ b/lib/public/AppFramework/Services/InitialStateProvider.php
@@ -42,7 +42,9 @@ abstract class InitialStateProvider implements \JsonSerializable {
 
 	/**
 	 * @since 21.0.0
+	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	final public function jsonSerialize() {
 		return $this->getData();
 	}
diff --git a/lib/public/Dashboard/Model/WidgetSetting.php b/lib/public/Dashboard/Model/WidgetSetting.php
index c456c63f4f5..fce59a4350b 100644
--- a/lib/public/Dashboard/Model/WidgetSetting.php
+++ b/lib/public/Dashboard/Model/WidgetSetting.php
@@ -230,10 +230,8 @@ final class WidgetSetting implements JsonSerializable {
 	/**
 	 * @since 15.0.0
 	 * @deprecated 20.0.0
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'name' => $this->getName(),
 			'title' => $this->getTitle(),
diff --git a/lib/public/Dashboard/Model/WidgetSetup.php b/lib/public/Dashboard/Model/WidgetSetup.php
index 1cc8d9ff561..f3e09dcc71b 100644
--- a/lib/public/Dashboard/Model/WidgetSetup.php
+++ b/lib/public/Dashboard/Model/WidgetSetup.php
@@ -261,10 +261,8 @@ final class WidgetSetup implements JsonSerializable {
 	/**
 	 * @since 15.0.0
 	 * @deprecated 20.0.0
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'size' => $this->getSizes(),
 			'menu' => $this->getMenuEntries(),
diff --git a/lib/public/Dashboard/Model/WidgetTemplate.php b/lib/public/Dashboard/Model/WidgetTemplate.php
index e6f9742fed7..3521960c303 100644
--- a/lib/public/Dashboard/Model/WidgetTemplate.php
+++ b/lib/public/Dashboard/Model/WidgetTemplate.php
@@ -312,10 +312,8 @@ final class WidgetTemplate implements JsonSerializable {
 	/**
 	 * @since 15.0.0
 	 * @deprecated 20.0.0
-	 *
-	 * @return array
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'icon' => $this->getIcon(),
 			'css' => $this->getCss(),
diff --git a/lib/public/DirectEditing/ATemplate.php b/lib/public/DirectEditing/ATemplate.php
index c38fc898dab..53aff0d40ff 100644
--- a/lib/public/DirectEditing/ATemplate.php
+++ b/lib/public/DirectEditing/ATemplate.php
@@ -57,9 +57,8 @@ abstract class ATemplate implements JsonSerializable {
 
 	/**
 	 * @since 18.0.0
-	 * @return array|mixed
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'id' => $this->getId(),
 			'title' => $this->getTitle(),
diff --git a/lib/public/EventDispatcher/GenericEvent.php b/lib/public/EventDispatcher/GenericEvent.php
index e78ae1827a1..1ba1cc6da14 100644
--- a/lib/public/EventDispatcher/GenericEvent.php
+++ b/lib/public/EventDispatcher/GenericEvent.php
@@ -156,7 +156,9 @@ class GenericEvent extends Event implements ArrayAccess, IteratorAggregate {
 	 * @link https://php.net/manual/en/arrayaccess.offsetget.php
 	 * @since 18.0.0
 	 * @deprecated 22.0.0
+	 * @return mixed
 	 */
+	#[\ReturnTypeWillChange]
 	public function offsetGet($offset) {
 		return $this->arguments[$offset];
 	}
diff --git a/lib/public/Files/Template/Template.php b/lib/public/Files/Template/Template.php
index 50d8b406be9..d71ef3b3655 100644
--- a/lib/public/Files/Template/Template.php
+++ b/lib/public/Files/Template/Template.php
@@ -69,7 +69,7 @@ final class Template implements \JsonSerializable {
 	/**
 	 * @since 21.0.0
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'templateType' => $this->templateType,
 			'templateId' => $this->templateId,
diff --git a/lib/public/Files/Template/TemplateFileCreator.php b/lib/public/Files/Template/TemplateFileCreator.php
index 7be45e68ef9..26edf585869 100644
--- a/lib/public/Files/Template/TemplateFileCreator.php
+++ b/lib/public/Files/Template/TemplateFileCreator.php
@@ -106,7 +106,7 @@ final class TemplateFileCreator implements \JsonSerializable {
 	/**
 	 * @since 21.0.0
 	 */
-	public function jsonSerialize() {
+	public function jsonSerialize(): array {
 		return [
 			'app' => $this->appId,
 			'label' => $this->actionName,
diff --git a/tests/lib/InitialStateServiceTest.php b/tests/lib/InitialStateServiceTest.php
index 2a23774baf1..db4c98b20cf 100644
--- a/tests/lib/InitialStateServiceTest.php
+++ b/tests/lib/InitialStateServiceTest.php
@@ -54,7 +54,7 @@ class InitialStateServiceTest extends TestCase {
 			[23],
 			[2.3],
 			[new class implements JsonSerializable {
-				public function jsonSerialize() {
+				public function jsonSerialize(): int {
 					return 3;
 				}
 			}],