11 files declare their use of RequestContext

IFrameUrlHelper.php in core/modules/media/src/IFrameUrlHelper.php
IFrameUrlHelperTest.php in core/modules/media/tests/src/Unit/IFrameUrlHelperTest.php
PathBasedBreadcrumbBuilder.php in core/modules/system/src/PathBasedBreadcrumbBuilder.php
PathValidator.php in core/lib/Drupal/Core/Path/PathValidator.php
PathValidatorTest.php in core/tests/Drupal/KernelTests/Core/Path/PathValidatorTest.php
RedirectResponseSubscriber.php in core/lib/Drupal/Core/EventSubscriber/RedirectResponseSubscriber.php
RouterTest.php in core/tests/Drupal/Tests/Core/Routing/RouterTest.php
SiteInformationForm.php in core/modules/system/src/Form/SiteInformationForm.php
TrustedRedirectResponseTest.php in core/tests/Drupal/Tests/Core/Routing/TrustedRedirectResponseTest.php
UrlGeneratorTest.php in core/tests/Drupal/Tests/Core/Routing/UrlGeneratorTest.php
UserAuthTest.php in core/modules/user/tests/src/Unit/UserAuthTest.php

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