SharedPreferences under Delegated properties

SomeManagers.kt

//SomeManager.kt
interface SomeManager {
    var userId: Long?
    var userName: String?

    /**
     * Returns true if user valid.
     */
    fun isUserValid(): Boolean

    /**
     * Logout action clear all users data.
     */
    fun clear()
}

//SomeManagerImpl.kt
class SomeManagerImpl(context: Context) : SharedPreferencesProvider, RegistrationManager {
    private val cacheCleaners = mutableListOf<(() -> Unit)>()
    private val masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC)

    override val preferences: SharedPreferences = EncryptedSharedPreferences.create(
        getPrefName("userCreds"), masterKeyAlias, context,
        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
    )

    //The by keyword indicates that the property is controlled by the provided delegate instead of its own field.
    override var userId: Long? by PreferencesDelegate<Long?>(::userId.name).addCacheCleaners(cacheCleaners)
    override var userName: String? by PreferencesDelegate<String?>(::userName.name).addCacheCleaners(cacheCleaners)
   
   
    override fun isUserValid(): Boolean = userId != null

    override fun clear() {
        cacheCleaners.forEach { it.invoke() }
        preferences.run { edit().clear().commit() }
    }
}