8 files declare their use of KeyInterface in Key 8

ConfigKeyProvider.php in src/Plugin/KeyProvider/ConfigKeyProvider.php

EnvKeyProvider.php in src/Plugin/KeyProvider/EnvKeyProvider.php

FileKeyProvider.php in src/Plugin/KeyProvider/FileKeyProvider.php

Key.php in src/Entity/Key.php

KeyProviderBase.php in src/Plugin/KeyProviderBase.php

KeyProviderInterface.php in src/Plugin/KeyProviderInterface.php

KeyProviderSettableValueInterface.php in src/Plugin/KeyProviderSettableValueInterface.php

State.php in tests/modules/key_test/src/Plugin/KeyProvider/State.php