Kotlin is basically Java without the boilerplate. Some of the code snippets on the page, translated into Kotlin, would be:
data class User(val username: String)
data class Config(val userTable: DynamoTable, val userId: String)
typealias ItemToUserConverter = (Item) -> User
class DynamoDbUserProvider(
val configProvider: ConfigProvider,
val userTableProvider: UserTableProvider,
val dynamoReader: DynamoItemReader,
val itemToUserConverter: ItemToUserConverter) {
fun execute(id: String) = itemToUserConverter(dynamoReader.execute(userTableProvider.execute(config), id))
}