mapbox sdk + gsimap (kotlin)

MainActivity.kt

package org.smellman.mapboxsdktest

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import com.mapbox.mapboxsdk.api.ILatLng
import com.mapbox.mapboxsdk.geometry.LatLng
import com.mapbox.mapboxsdk.tileprovider.tilesource.WebSourceTileLayer
import com.mapbox.mapboxsdk.views.MapView

public class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val mv:MapView = findViewById(R.id.mapview) as MapView
        mv.setTileSource(WebSourceTileLayer("gsi_std","http://cyberjapandata.gsi.go.jp/xyz/std/{z}/{x}/{y}.png"))
        val defaultCenter:ILatLng = LatLng(35.362222, 138.731389)
        mv.setCenter(defaultCenter)
        val defaultZoom:Float = 5f
        mv.setZoom(defaultZoom)
    }

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the menu; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.menu_main, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        val id = item.itemId

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true
        }

        return super.onOptionsItemSelected(item)
    }
}