Migrate to Kotlin API

Author: Mygod

core/build.gradle

@@ -54,10 +54,10 @@ def roomVersion = '2.2.3'
 def workVersion = '2.2.0'
 dependencies {
     api project(':plugin')
+    api 'androidx.activity:activity-ktx:1.1.0-rc03'
     api "androidx.lifecycle:lifecycle-common-java8:$lifecycleVersion"
     api "androidx.lifecycle:lifecycle-extensions:$lifecycleVersion"
     api "androidx.lifecycle:lifecycle-livedata-core-ktx:$lifecycleVersion"
-    api "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycleVersion"
     api 'androidx.preference:preference:1.1.0'
     api "androidx.room:room-runtime:$roomVersion"
     api "androidx.work:work-runtime-ktx:$workVersion"

mobile/src/main/java/com/github/shadowsocks/subscription/SubscriptionFragment.kt

@@ -41,7 +41,6 @@ import androidx.recyclerview.widget.RecyclerView
 import com.github.shadowsocks.MainActivity
 import com.github.shadowsocks.R
 import com.github.shadowsocks.ToolbarFragment
-import com.github.shadowsocks.bg.BaseService
 import com.github.shadowsocks.plugin.AlertDialogFragment
 import com.github.shadowsocks.utils.readableMessage
 import com.github.shadowsocks.widget.ListHolderListener

mobile/src/main/java/com/github/shadowsocks/widget/StatsBar.kt

@@ -25,10 +25,9 @@ import android.text.format.Formatter
 import android.util.AttributeSet
 import android.view.View
 import android.widget.TextView
+import androidx.activity.viewModels
 import androidx.appcompat.widget.TooltipCompat
 import androidx.coordinatorlayout.widget.CoordinatorLayout
-import androidx.lifecycle.ViewModelProvider
-import androidx.lifecycle.get
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.observe
 import com.github.shadowsocks.MainActivity
@@ -47,7 +46,7 @@ class StatsBar @JvmOverloads constructor(context: Context, attrs: AttributeSet?
     private lateinit var rxText: TextView
     private lateinit var txRateText: TextView
     private lateinit var rxRateText: TextView
-    private val tester = ViewModelProvider(context as MainActivity).get<HttpsTest>()
+    private val tester by (context as MainActivity).viewModels<HttpsTest>()
     private lateinit var behavior: Behavior
     override fun getBehavior(): Behavior {
         if (!this::behavior.isInitialized) behavior = object : Behavior() {