6 files declare their use of FlashBag in Zircon Profile 8.0

FlashBagTest.php in vendor/symfony/http-foundation/Tests/Session/Flash/FlashBagTest.php

MockArraySessionStorageTest.php in vendor/symfony/http-foundation/Tests/Session/Storage/MockArraySessionStorageTest.php

MockFileSessionStorageTest.php in vendor/symfony/http-foundation/Tests/Session/Storage/MockFileSessionStorageTest.php

NativeSessionStorageTest.php in vendor/symfony/http-foundation/Tests/Session/Storage/NativeSessionStorageTest.php

Session.php in vendor/symfony/http-foundation/Session/Session.php

SessionTest.php in vendor/symfony/http-foundation/Tests/Session/SessionTest.php