title: Databinding not work together with viewbinding in Kotlin
body: <p><strong>Android Studio 3.6</strong></p>
  
  <p>build.gradle:</p>
  
  <pre><code>buildscript {
      ext.kotlin_version = '1.3.50'
      repositories {
          google()
          jcenter()
  
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.6.0-beta01'
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
  </code></pre>
  
  <p>in app/build.gradle:</p>
  
  <pre><code>android {
      viewBinding.enabled = true
      dataBinding {
          enabled = true
      }
  </code></pre>
  
  <p>in my activity:</p>
  
  <pre><code>import android.os.Bundle
  import android.util.Log
  import androidx.appcompat.app.AppCompatActivity
  import androidx.viewpager2.widget.ViewPager2
  
  import com.myproject.BuildConfig
  import com.myproject.R
  import com.myproject.adapter.CustomFragmentStateAdapter
  import com.myproject.databinding.QrBluetoothSwipeActivityBinding
  import com.myproject.ui.fragment.BluetoothPageFragment
  import com.myproject.ui.fragment.QrPageFragment
  import androidx.databinding.DataBindingUtil
  import androidx.databinding.ObservableInt
  
  class QRBluetoothSwipeActivity : AppCompatActivity() {
      private lateinit var viewBinding: QrBluetoothSwipeActivityBinding
      var positionObservable = ObservableInt()
  
      companion object {
          private val TAG = QRBluetoothSwipeActivity::class.java.name
      }
  
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)  
  
           // databinding init
          val binding = DataBindingUtil.setContentView&lt;QrBluetoothSwipeActivityBinding&gt;(
              this, R.layout.qr_bluetooth_swipe_activity
          )
          binding.setHandler(this)
  
          // viewbinding init
          viewBinding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)
          setContentView(viewBinding.root)
  
          init()
      }
  
   private fun init() {
          val customFragmentStateAdapter = CustomFragmentStateAdapter(this)
          customFragmentStateAdapter.addFragment(QrPageFragment())
          customFragmentStateAdapter.addFragment(BluetoothPageFragment())
          viewBinding.viewPager2.adapter = customFragmentStateAdapter
  
          viewBinding.viewPager2.registerOnPageChangeCallback(object :
              ViewPager2.OnPageChangeCallback() {
              override fun onPageSelected(position: Int) {
                  if (BuildConfig.DEBUG) {
                      Log.d(TAG, "registerOnPageChangeCallback: position = $position")
                  }
                  positionObservable.set(position)
              }
          })
      }
  </code></pre>
  
  <p>my <strong>qr_bluetooth_swipe_activity.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;layout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"&gt;
  
      &lt;data&gt;
  
          &lt;import type="android.view.View" /&gt;
  
          &lt;variable
              name="handler"
              type="com.myproject.actviity.QRBluetoothSwipeActivity" /&gt;
  
      &lt;/data&gt;
  
      &lt;androidx.constraintlayout.widget.ConstraintLayout
          android:layout_width="match_parent"
          android:layout_height="match_parent"&gt;
  
          &lt;androidx.viewpager2.widget.ViewPager2
              android:id="@+id/viewPager2"
              android:layout_width="0dp"
              android:layout_height="0dp"
              app:layout_constraintBottom_toTopOf="@+id/bottonContainer"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent" /&gt;
  
          &lt;androidx.constraintlayout.widget.ConstraintLayout
              android:id="@+id/bottonContainer"
              android:layout_width="0dp"
              android:layout_height="104dp"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"&gt;
  
              &lt;androidx.constraintlayout.widget.ConstraintLayout
                  android:id="@+id/qrBottonMainContainer"
                  android:layout_width="0dp"
                  android:layout_height="104dp"
                  android:visibility="@{handler.positionObservable == 0 ? View.GONE: View.VISIBLE}"
                  app:layout_constraintBottom_toBottomOf="parent"
                  app:layout_constraintEnd_toEndOf="parent"
                  app:layout_constraintStart_toStartOf="parent"/&gt;
  </code></pre>
  
  <p>After start app then success swipe <strong>viewpager2</strong>.
  And as result success show the next message:</p>
  
  <pre><code>10-25 14:25:24.991 D/com.myproject.actviity.QRBluetoothSwipeActivity(23012): registerOnPageChangeCallback: position = 0
  </code></pre>
  
  <p>nice. 
  But <code>qrBottonMainContainer</code> not hide. Why?</p>
  
  <p>P.S. If I remove this:</p>
  
  <pre><code>viewBinding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)
  setContentView(viewBinding.root)
  </code></pre>
  
  <p>then success work.</p>
  
  <p>why?</p>