Help coding bukkit plugin with kotlin.

KotlinPlugin.kt

import org.bukkit.Bukkit
import org.bukkit.OfflinePlayer
import org.bukkit.plugin.java.JavaPlugin
import java.util.*

/**
 * Created by Basix on 16. 2. 14.
 * Help develop plugin with kotlin.
 *
 * @author Basix
 */

fun doCommand(f: () -> Unit): Boolean {
    /**
     * This is lambda function for onCommand method.
     * override fun onCommand(sender: CommandSender, cmd: Command, label: String, args: Array<String>) = when (cmd.label){
     *     "command" -> doCommand{ }
     *     else -> false
     * }
     * @param () -> Unit
     */
    f()
    return true
}

/**
 * Works with UUIDFetcher.
 *
 * @param PlayerName, plugin
 */
fun getOfflinePlayer(PlayerName: String, plugin: JavaPlugin): OfflinePlayer {
    val fetcher = UUIDFetcher(Arrays.asList(PlayerName))
    var response: Map<String, UUID> = kotlin.collections.emptyMap()
    try {
        response = fetcher.call()
    } catch (e: Exception) {
        plugin.logger.warning("Exception while running UUIDFetcher")
        e.printStackTrace()
    }
    return Bukkit.getOfflinePlayer(response.get(PlayerName))
}