generic resource sealed class kotlin android

sealed class Resource<T>(
        val data: T? = null,
        val message: String? = null
) {
    class Success<T>(data: T) : Resource<T>(data)
    class Loading<T>(data: T? = null, var refreshing: Boolean = false) : Resource<T>(data)
    class Error<T>(data: T? = null, message: String) : Resource<T>(data, message)
}

sealed class ResponseState<out T> {
    object Loading : ResponseState<Nothing>()
    data class Error(val throwable: Throwable) : ResponseState<Nothing>()
    data class Success<T>(val item: T) : ResponseState<T>()
}