diff --git a/automatic_updates_extensions/src/Validator/UpdateReleaseValidator.php b/automatic_updates_extensions/src/Validator/UpdateReleaseValidator.php
index ac778868ba49fdd8f4503c048896b934cc379936..c4786cfb77a0fb565b31b7d99cabe8057126130a 100644
--- a/automatic_updates_extensions/src/Validator/UpdateReleaseValidator.php
+++ b/automatic_updates_extensions/src/Validator/UpdateReleaseValidator.php
@@ -103,7 +103,7 @@ final class UpdateReleaseValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'checkRelease',
     ];
diff --git a/package_manager/src/EventSubscriber/UpdateDataSubscriber.php b/package_manager/src/EventSubscriber/UpdateDataSubscriber.php
index 8d6490bccaf05dca79140b9ff9fe7912ff7abb33..8b37898745c029bcb7ace0b2cfed9b4d502606e1 100644
--- a/package_manager/src/EventSubscriber/UpdateDataSubscriber.php
+++ b/package_manager/src/EventSubscriber/UpdateDataSubscriber.php
@@ -48,7 +48,7 @@ final class UpdateDataSubscriber implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PostApplyEvent::class => ['clearData', 1000],
     ];
diff --git a/package_manager/src/PathExcluder/GitExcluder.php b/package_manager/src/PathExcluder/GitExcluder.php
index 5ec84d0680b9be69a8b22cfeb74faf03e1314862..d354c2abfa2f1011421544a2fb2e55f7705fa7b2 100644
--- a/package_manager/src/PathExcluder/GitExcluder.php
+++ b/package_manager/src/PathExcluder/GitExcluder.php
@@ -34,7 +34,7 @@ final class GitExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeGitDirectories',
       PreApplyEvent::class => 'excludeGitDirectories',
diff --git a/package_manager/src/PathExcluder/SiteConfigurationExcluder.php b/package_manager/src/PathExcluder/SiteConfigurationExcluder.php
index 9b626df17e0be6514da5e165533e0297a71c0d48..41a3c4af6ba577dd0e399617ef9539fb5da15c28 100644
--- a/package_manager/src/PathExcluder/SiteConfigurationExcluder.php
+++ b/package_manager/src/PathExcluder/SiteConfigurationExcluder.php
@@ -69,7 +69,7 @@ class SiteConfigurationExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeSiteConfiguration',
       PreApplyEvent::class => 'excludeSiteConfiguration',
diff --git a/package_manager/src/PathExcluder/SiteFilesExcluder.php b/package_manager/src/PathExcluder/SiteFilesExcluder.php
index 13b8ac640beb62561279b64909a5edd3cdfec49e..498a1dd4dcb081b6dfe3413d2c2bd692da1f96a3 100644
--- a/package_manager/src/PathExcluder/SiteFilesExcluder.php
+++ b/package_manager/src/PathExcluder/SiteFilesExcluder.php
@@ -56,7 +56,7 @@ final class SiteFilesExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeSiteFiles',
       PreApplyEvent::class => 'excludeSiteFiles',
diff --git a/package_manager/src/PathExcluder/SqliteDatabaseExcluder.php b/package_manager/src/PathExcluder/SqliteDatabaseExcluder.php
index cd8ba76f3df6e90beb36f10b3c95238306b4ad32..78214dcb06c18d1f5dc9b5496bd599f5faf455b7 100644
--- a/package_manager/src/PathExcluder/SqliteDatabaseExcluder.php
+++ b/package_manager/src/PathExcluder/SqliteDatabaseExcluder.php
@@ -44,7 +44,7 @@ class SqliteDatabaseExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeDatabaseFiles',
       PreApplyEvent::class => 'excludeDatabaseFiles',
diff --git a/package_manager/src/PathExcluder/TestSiteExcluder.php b/package_manager/src/PathExcluder/TestSiteExcluder.php
index d796e07e5c0fe3a3c942b3f13d84d6128a878f8d..96d361bfca0dcaf3341dc86b13e010430affd25d 100644
--- a/package_manager/src/PathExcluder/TestSiteExcluder.php
+++ b/package_manager/src/PathExcluder/TestSiteExcluder.php
@@ -33,7 +33,7 @@ final class TestSiteExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeTestSites',
       PreApplyEvent::class => 'excludeTestSites',
diff --git a/package_manager/src/PathExcluder/VendorHardeningExcluder.php b/package_manager/src/PathExcluder/VendorHardeningExcluder.php
index e54ff986f51f3f7022ad14abd26c7973e6425ff4..1cb6959faab0faaff4dea866e9478348a0fc02ef 100644
--- a/package_manager/src/PathExcluder/VendorHardeningExcluder.php
+++ b/package_manager/src/PathExcluder/VendorHardeningExcluder.php
@@ -33,7 +33,7 @@ final class VendorHardeningExcluder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'excludeVendorHardeningFiles',
       PreApplyEvent::class => 'excludeVendorHardeningFiles',
diff --git a/package_manager/src/Validator/ComposerExecutableValidator.php b/package_manager/src/Validator/ComposerExecutableValidator.php
index 8e99ac8789121e941c301faf243579749d145959..280883ce133c18034e436da601e9c4d46389fc4e 100644
--- a/package_manager/src/Validator/ComposerExecutableValidator.php
+++ b/package_manager/src/Validator/ComposerExecutableValidator.php
@@ -125,7 +125,7 @@ final class ComposerExecutableValidator implements EventSubscriberInterface, Pro
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/ComposerPatchesValidator.php b/package_manager/src/Validator/ComposerPatchesValidator.php
index 9a930e06ad0c3301165b9f72b667e5baa3b97b3b..ed5fc004ee9d9a5783b2e08c01c14ecb1281c561 100644
--- a/package_manager/src/Validator/ComposerPatchesValidator.php
+++ b/package_manager/src/Validator/ComposerPatchesValidator.php
@@ -41,7 +41,7 @@ class ComposerPatchesValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/ComposerSettingsValidator.php b/package_manager/src/Validator/ComposerSettingsValidator.php
index c80aecbd07f3b86eb5b415b88f57d1acae1edccb..ee6556b289215d73b9b96266c98f67b161f4bff3 100644
--- a/package_manager/src/Validator/ComposerSettingsValidator.php
+++ b/package_manager/src/Validator/ComposerSettingsValidator.php
@@ -52,7 +52,7 @@ final class ComposerSettingsValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/DiskSpaceValidator.php b/package_manager/src/Validator/DiskSpaceValidator.php
index 7c8e4842cc8d44524521762df01befbce5306f82..fa6d0ab01e470159a7e8a8bf6a183759fed13c58 100644
--- a/package_manager/src/Validator/DiskSpaceValidator.php
+++ b/package_manager/src/Validator/DiskSpaceValidator.php
@@ -164,7 +164,7 @@ class DiskSpaceValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/DuplicateInfoFileValidator.php b/package_manager/src/Validator/DuplicateInfoFileValidator.php
index fe1611d330eb87074f727462372622e2d9299eef..3cfe75381326be0677f0f8dceab67b98ebffa827 100644
--- a/package_manager/src/Validator/DuplicateInfoFileValidator.php
+++ b/package_manager/src/Validator/DuplicateInfoFileValidator.php
@@ -76,7 +76,7 @@ class DuplicateInfoFileValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreApplyEvent::class => 'validateDuplicateInfoFileInStage',
     ];
diff --git a/package_manager/src/Validator/EnvironmentSupportValidator.php b/package_manager/src/Validator/EnvironmentSupportValidator.php
index 8e124b9b3e9be375ec1cbf8b90e72735e34e5008..8dc8eea34e30ae606fb6a0268b48a986446abfa3 100644
--- a/package_manager/src/Validator/EnvironmentSupportValidator.php
+++ b/package_manager/src/Validator/EnvironmentSupportValidator.php
@@ -61,7 +61,7 @@ final class EnvironmentSupportValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => ['validateStagePreOperation', 200],
       StatusCheckEvent::class => ['validateStagePreOperation', 200],
diff --git a/package_manager/src/Validator/LockFileValidator.php b/package_manager/src/Validator/LockFileValidator.php
index c95eb763200bf638d7ea7e251c6106cd5f1032fc..23c144a107464d9c7d870bad46b3e0df87431a77 100644
--- a/package_manager/src/Validator/LockFileValidator.php
+++ b/package_manager/src/Validator/LockFileValidator.php
@@ -154,7 +154,7 @@ final class LockFileValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'storeHash',
       PreRequireEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/MultisiteValidator.php b/package_manager/src/Validator/MultisiteValidator.php
index c8f3b0ed6fe7ff92d7c51181b2c30b345b3810d1..453842016fd249a032085b91da08bc204ca65794 100644
--- a/package_manager/src/Validator/MultisiteValidator.php
+++ b/package_manager/src/Validator/MultisiteValidator.php
@@ -72,7 +72,7 @@ final class MultisiteValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/OverwriteExistingPackagesValidator.php b/package_manager/src/Validator/OverwriteExistingPackagesValidator.php
index eec6993f313a6b36f058f5ea67fe95c35be5f87b..d338241cbd13ce6a5c13dbc52d4d555918ec0200 100644
--- a/package_manager/src/Validator/OverwriteExistingPackagesValidator.php
+++ b/package_manager/src/Validator/OverwriteExistingPackagesValidator.php
@@ -75,7 +75,7 @@ final class OverwriteExistingPackagesValidator implements EventSubscriberInterfa
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreApplyEvent::class => 'validateStagePreOperation',
     ];
diff --git a/package_manager/src/Validator/PendingUpdatesValidator.php b/package_manager/src/Validator/PendingUpdatesValidator.php
index b51e35a7534433c579acb4f5bc2fdab9e0d0c716..c68b7d89ba70a29b46f854dd1568c7ebc3a4ea42 100644
--- a/package_manager/src/Validator/PendingUpdatesValidator.php
+++ b/package_manager/src/Validator/PendingUpdatesValidator.php
@@ -86,7 +86,7 @@ final class PendingUpdatesValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/SettingsValidator.php b/package_manager/src/Validator/SettingsValidator.php
index 63d9d74016439b57e8056efd7f1c51a23b51fbfe..8139fe21692c43ba484c565895c694400d6d5227 100644
--- a/package_manager/src/Validator/SettingsValidator.php
+++ b/package_manager/src/Validator/SettingsValidator.php
@@ -46,7 +46,7 @@ final class SettingsValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/StagedDBUpdateValidator.php b/package_manager/src/Validator/StagedDBUpdateValidator.php
index d131f834bfe11df4e1752006c0ed6b9efe9e7cd1..da53bc1f75e8126c7e2843155c36290fb75348dc 100644
--- a/package_manager/src/Validator/StagedDBUpdateValidator.php
+++ b/package_manager/src/Validator/StagedDBUpdateValidator.php
@@ -152,7 +152,7 @@ class StagedDBUpdateValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       StatusCheckEvent::class => 'checkForStagedDatabaseUpdates',
     ];
diff --git a/package_manager/src/Validator/SupportedReleaseValidator.php b/package_manager/src/Validator/SupportedReleaseValidator.php
index 780cda00ceb8983717a85099502badb9ad82d8af..dd034576a89f5a766b289c9587e4ac60e6182553 100644
--- a/package_manager/src/Validator/SupportedReleaseValidator.php
+++ b/package_manager/src/Validator/SupportedReleaseValidator.php
@@ -117,7 +117,7 @@ final class SupportedReleaseValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreApplyEvent::class => 'checkStagedReleases',
     ];
diff --git a/package_manager/src/Validator/SymlinkValidator.php b/package_manager/src/Validator/SymlinkValidator.php
index 925df7b22c7bcdda2ab073e5f5f2da47a5d0a1cf..0035f46d921b5d240d773610f1982be6bf128794 100644
--- a/package_manager/src/Validator/SymlinkValidator.php
+++ b/package_manager/src/Validator/SymlinkValidator.php
@@ -122,7 +122,7 @@ class SymlinkValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       PreApplyEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/WritableFileSystemValidator.php b/package_manager/src/Validator/WritableFileSystemValidator.php
index 7badb57765be7fd42b8858c312131dc5aee3e764..4454d9f8637194914b7f18c295bd47bac2b70463 100644
--- a/package_manager/src/Validator/WritableFileSystemValidator.php
+++ b/package_manager/src/Validator/WritableFileSystemValidator.php
@@ -94,7 +94,7 @@ class WritableFileSystemValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       StatusCheckEvent::class => 'validateStagePreOperation',
diff --git a/package_manager/src/Validator/XdebugValidator.php b/package_manager/src/Validator/XdebugValidator.php
index a8bd959ae8cccc66957a365293543e1c8b6a2522..b17cb40b66bca40fa69d899af9106ac79186feb7 100644
--- a/package_manager/src/Validator/XdebugValidator.php
+++ b/package_manager/src/Validator/XdebugValidator.php
@@ -36,7 +36,7 @@ final class XdebugValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       StatusCheckEvent::class => 'checkForXdebug',
     ];
diff --git a/package_manager/tests/fixtures/updated_module/1.1.0/src/PostApplySubscriber.php b/package_manager/tests/fixtures/updated_module/1.1.0/src/PostApplySubscriber.php
index 2e7e988a3b77850d9aa84692dfccdf0980a71a10..94092531f17cfb22fef647c41443c1c52058f3ef 100644
--- a/package_manager/tests/fixtures/updated_module/1.1.0/src/PostApplySubscriber.php
+++ b/package_manager/tests/fixtures/updated_module/1.1.0/src/PostApplySubscriber.php
@@ -43,7 +43,7 @@ class PostApplySubscriber implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PostApplyEvent::class => 'postApply',
     ];
diff --git a/package_manager/tests/modules/package_manager_test_validation/src/EventSubscriber/TestSubscriber.php b/package_manager/tests/modules/package_manager_test_validation/src/EventSubscriber/TestSubscriber.php
index 80a5ac26a420b6709cb397c4a50ccfe7c630b552..02ea05925ee9c5869caf4bbcbc48ba406e5a1754 100644
--- a/package_manager/tests/modules/package_manager_test_validation/src/EventSubscriber/TestSubscriber.php
+++ b/package_manager/tests/modules/package_manager_test_validation/src/EventSubscriber/TestSubscriber.php
@@ -154,7 +154,7 @@ class TestSubscriber implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $priority = defined('PACKAGE_MANAGER_TEST_VALIDATOR_PRIORITY') ? PACKAGE_MANAGER_TEST_VALIDATOR_PRIORITY : 5;
 
     return [
diff --git a/package_manager/tests/src/Kernel/EnvironmentSupportValidatorTest.php b/package_manager/tests/src/Kernel/EnvironmentSupportValidatorTest.php
index bef49a244a766e4649792b293aeef628d0ec09aa..450c0fb7fe56b3753b3e1d3ee4173ac33f80e1b6 100644
--- a/package_manager/tests/src/Kernel/EnvironmentSupportValidatorTest.php
+++ b/package_manager/tests/src/Kernel/EnvironmentSupportValidatorTest.php
@@ -26,7 +26,7 @@ class EnvironmentSupportValidatorTest extends PackageManagerKernelTestBase imple
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $map = function (): string {
       return 'assertValidationStopped';
     };
diff --git a/package_manager/tests/src/Kernel/StageEventsTest.php b/package_manager/tests/src/Kernel/StageEventsTest.php
index 78c99844177214d7ad189bc34a50401e9230daa6..d5aa37a87f5eaa18918d5eaafeea05c664063109 100644
--- a/package_manager/tests/src/Kernel/StageEventsTest.php
+++ b/package_manager/tests/src/Kernel/StageEventsTest.php
@@ -62,7 +62,7 @@ class StageEventsTest extends PackageManagerKernelTestBase implements EventSubsc
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'handleEvent',
       PostCreateEvent::class => 'handleEvent',
diff --git a/src/EventSubscriber/ConfigSubscriber.php b/src/EventSubscriber/ConfigSubscriber.php
index 4d8781f42b59c2a279816bc9dee182e941219256..893633c4625c13c328c26fb3c4e692d93c3c68e9 100644
--- a/src/EventSubscriber/ConfigSubscriber.php
+++ b/src/EventSubscriber/ConfigSubscriber.php
@@ -22,7 +22,7 @@ final class ConfigSubscriber implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       ConfigEvents::SAVE => 'onConfigSave',
     ];
diff --git a/src/Routing/RouteSubscriber.php b/src/Routing/RouteSubscriber.php
index 3b794b7115063f932bdd0faef2f97c2317e23aed..51e65eef3aee017672ea4b9c8ec13d8edb4e63f7 100644
--- a/src/Routing/RouteSubscriber.php
+++ b/src/Routing/RouteSubscriber.php
@@ -21,7 +21,7 @@ final class RouteSubscriber extends RouteSubscriberBase {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       // Try to run after other route subscribers, to minimize the chances of
       // conflicting with other code that is modifying Update module routes.
diff --git a/src/Validation/ReadinessValidationManager.php b/src/Validation/ReadinessValidationManager.php
index 1873e412560236798ef38fb46cce7245050c81c7..51c17825e75ada23f2c57759d1620824d4e70f82 100644
--- a/src/Validation/ReadinessValidationManager.php
+++ b/src/Validation/ReadinessValidationManager.php
@@ -170,7 +170,7 @@ final class ReadinessValidationManager implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PostApplyEvent::class => 'clearStoredResults',
     ];
diff --git a/src/Validator/CronFrequencyValidator.php b/src/Validator/CronFrequencyValidator.php
index c7fe3ae4807bf574c5cf999d78291fae82a20348..e431c1e979ffd3820769fda4080b0d1985cd6bd1 100644
--- a/src/Validator/CronFrequencyValidator.php
+++ b/src/Validator/CronFrequencyValidator.php
@@ -187,7 +187,7 @@ class CronFrequencyValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       StatusCheckEvent::class => 'checkCronFrequency',
     ];
diff --git a/src/Validator/CronServerValidator.php b/src/Validator/CronServerValidator.php
index ac3fa0bd45a0c37ce2ef2aac98dccc7f7f1050da..41e3fe3e61f18dc383bad3f85b5daafde3801f65 100644
--- a/src/Validator/CronServerValidator.php
+++ b/src/Validator/CronServerValidator.php
@@ -113,7 +113,7 @@ final class CronServerValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'checkServer',
       StatusCheckEvent::class => 'checkServer',
diff --git a/src/Validator/ScaffoldFilePermissionsValidator.php b/src/Validator/ScaffoldFilePermissionsValidator.php
index 2e214909f352252f1f8bd18f84818e2cb7e6e7f9..92a136a1bec568e9c7092049ec1f2fb1039272c4 100644
--- a/src/Validator/ScaffoldFilePermissionsValidator.php
+++ b/src/Validator/ScaffoldFilePermissionsValidator.php
@@ -126,7 +126,7 @@ final class ScaffoldFilePermissionsValidator implements EventSubscriberInterface
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'validateStagePreOperation',
       PreApplyEvent::class => 'validateStagePreOperation',
diff --git a/src/Validator/StagedDatabaseUpdateValidator.php b/src/Validator/StagedDatabaseUpdateValidator.php
index 70949123473aec21c2729f8836bd7c0b1e07d8b8..8bc6181d2f8494fbebfc49812a645ed23f1e551f 100644
--- a/src/Validator/StagedDatabaseUpdateValidator.php
+++ b/src/Validator/StagedDatabaseUpdateValidator.php
@@ -62,7 +62,7 @@ class StagedDatabaseUpdateValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreApplyEvent::class => 'checkUpdateHooks',
     ];
diff --git a/src/Validator/StagedProjectsValidator.php b/src/Validator/StagedProjectsValidator.php
index 1e379c1a06168fb611cb845d3e53f8d7910208d2..3c01ab20138d5d880a1d4013d6b9c1ca959308b0 100644
--- a/src/Validator/StagedProjectsValidator.php
+++ b/src/Validator/StagedProjectsValidator.php
@@ -139,7 +139,7 @@ final class StagedProjectsValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[PreApplyEvent::class][] = ['validateStagedProjects'];
     return $events;
   }
diff --git a/src/Validator/VersionPolicyValidator.php b/src/Validator/VersionPolicyValidator.php
index 3ca70907ce1d18ddf2c0cc4c1ec60f82aadc89ce..f0373ad6376ca144231f9c481f2eb705a6c2bde2 100644
--- a/src/Validator/VersionPolicyValidator.php
+++ b/src/Validator/VersionPolicyValidator.php
@@ -253,7 +253,7 @@ final class VersionPolicyValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'checkVersion',
       StatusCheckEvent::class => 'checkVersion',
diff --git a/src/Validator/XdebugValidator.php b/src/Validator/XdebugValidator.php
index 28446ea6b9bade736ebb70ca4ba97437753e7f94..77fae3fd94b9f15664217894dfba40aba17ce9f0 100644
--- a/src/Validator/XdebugValidator.php
+++ b/src/Validator/XdebugValidator.php
@@ -75,7 +75,7 @@ final class XdebugValidator implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreCreateEvent::class => 'checkForXdebug',
       StatusCheckEvent::class => 'checkForXdebug',
diff --git a/tests/modules/automatic_updates_test/src/EventSubscriber/RequestTimeRecorder.php b/tests/modules/automatic_updates_test/src/EventSubscriber/RequestTimeRecorder.php
index ce775c3b6db5ba56969e9f312d19595313a33099..805c40f7465c83affd4b3c45a05a0397646b2994 100644
--- a/tests/modules/automatic_updates_test/src/EventSubscriber/RequestTimeRecorder.php
+++ b/tests/modules/automatic_updates_test/src/EventSubscriber/RequestTimeRecorder.php
@@ -55,7 +55,7 @@ class RequestTimeRecorder implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       PreApplyEvent::class => 'updateState',
       PostApplyEvent::class => 'updateState',
diff --git a/tests/modules/automatic_updates_test2/src/EventSubscriber/TestSubscriber2.php b/tests/modules/automatic_updates_test2/src/EventSubscriber/TestSubscriber2.php
index 47863fcef54cb9eaa7dbe26c47e846537b138372..a0f67db427c5d8e2524f0ff4877732704b825aa1 100644
--- a/tests/modules/automatic_updates_test2/src/EventSubscriber/TestSubscriber2.php
+++ b/tests/modules/automatic_updates_test2/src/EventSubscriber/TestSubscriber2.php
@@ -13,7 +13,7 @@ class TestSubscriber2 extends TestSubscriber1 {
 
   protected const STATE_KEY = 'automatic_updates_test2.checker_results';
 
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     $events[StatusCheckEvent::class][] = ['handleEvent', 4];
     $events[PreCreateEvent::class][] = ['handleEvent', 4];
 
diff --git a/tests/modules/automatic_updates_test_cron/src/Enabler.php b/tests/modules/automatic_updates_test_cron/src/Enabler.php
index e7cb069df4cf9a9ad4b32e895c850862ad3eae47..fd36bd7cb73941940f5133217440acebb577d43b 100644
--- a/tests/modules/automatic_updates_test_cron/src/Enabler.php
+++ b/tests/modules/automatic_updates_test_cron/src/Enabler.php
@@ -16,7 +16,7 @@ class Enabler implements EventSubscriberInterface {
   /**
    * {@inheritdoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       KernelEvents::REQUEST => 'enableCron',
     ];