I'm currently in a world where Interfaces are being used just to make references to classes instead of being used to assure implementation of the interface, let me present you an example

interface DumbInterface {

    fun one()

    fun two()
}

class DumbInterfaceImpl : DumbInterface {

    override fun one() {
        println("something")
    }

    override fun two() {
        println("else")
    }
}

And when I have something like this is acceptable:

interface NetworkErrorManager {

    fun handleRegistrationError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleResetPasswordError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleLoginError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleGetUserProfileError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleUpdateUserProfileError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleResendConfirmationEmailError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleRefreshUserTokenError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleLogoutError(statusCode: Int, errorBody: ResponseBody?): ApiException

    fun handleDeleteUserError(statusCode: Int, errorBody: ResponseBody?): ApiException
}

I've been trying to get people not to use interfaces when they are not being used as interfaces and just class references -- EXAMPLE: class JustDoingSomethingDumb(iNeedThisOtherDumbClass: DumbInterface ) instead of DumbInterfaceImpl -- and to use interfaces when we have easily recognizable patterns like this above and being receive with poker faces. When for exanmple, for the last example, I proposed something like:

interface Network{
    val statusCode: Int
    val errorBody: ResponseBody?
    val errorMessage: String
        get() = errorBody?.toString() ?: NetworkErrorManagerImpl.UNKNOWN_ERROR_MESSAGE

    fun get(): ApiException
}
sealed class NetworkImpl: Network{

    data class HandleRegistrationError(
        override val statusCode: Int,
        override val errorBody: ResponseBody?,
        override val errorMessage: String
    ) :NetworkImpl() {
        override fun get(): ApiException {
            return when (statusCode) {
                403 -> InvalidClient(
                    statusCode,
                    errorMessage
                )
                else -> handleOtherErrors(statusCode, errorMessage)
            }
        }
    }
}

Not saying the last one is the best but I needed some compromises as this NetwrokImpl holds handleOtherErrors which is just interesting for the realm of NetworkImpl

PS: NetworkErrorManager methods are not being implemented they are being used individually like NetworkErrorManagerImpl.handleRegistrationError(dumbParametersHere)