title: Unresolved reference. None of the following candidates is applicable because of receiver type mismatch
body: <p>I'm using <code>androidx navigation architecture</code> along with <code>Kotlin 1.2.71</code> in Android studio 3.2.1. My fragment code is:  </p>
  
  <pre><code>package com.dell.andnav.fragments
  
  import android.os.Bundle
  import android.support.v4.app.Fragment
  import android.view.LayoutInflater
  import android.view.View
  import android.view.ViewGroup
  import android.widget.Button
  import androidx.navigation.fragment.findNavController
  import com.dell.andnav.R
  import kotlinx.android.synthetic.main.fragment_welcome.*
  
  
  /**
   * A simple [Fragment] subclass.
   * Use the [WelcomeFragment.newInstance] factory method to
   * create an instance of this fragment.
   *
   */
  class WelcomeFragment : Fragment() {
  
      override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                                savedInstanceState: Bundle?): View? {
          // Inflate the layout for this fragment
          return inflater.inflate(R.layout.fragment_welcome, container, false)
      }
  
      override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
          super.onViewCreated(view, savedInstanceState)
          detailButton.setOnClickListener {
              findNavController().navigate(R.id.action_welcomeFragment_to_detailsFragment)
          }
      }
  
      companion object {
          @JvmStatic
          fun newInstance() = WelcomeFragment()
      }
  }  
  </code></pre>
  
  <p>And layout code is:  </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      android:id="@+id/frameLayout"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".fragments.WelcomeFragment"&gt;
  
  
      &lt;Button
          android:id="@+id/detailButton"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/to_detail_fragment"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toTopOf="parent" /&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;  
  </code></pre>
  
  <p>My build.gradle is:  </p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  apply plugin: 'androidx.navigation.safeargs'
  
  android {
      compileSdkVersion 28
      defaultConfig {
          applicationId "com.dell.andnav"
          minSdkVersion 21
          targetSdkVersion 28
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
          androidExtensions {
              experimental = true
          }
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      def nav_version = "1.0.0-alpha07"
      implementation fileTree(dir: 'libs', include: ['*.jar'])
  //    implementation 'com.android.support:appcompat-v7:28.0.0'
      implementation 'com.android.support.constraint:constraint-layout:1.1.3'
  //    implementation 'com.android.support:support-v4:28.0.0'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.2'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  
      implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'
      implementation 'androidx.legacy:legacy-support-v4:1.0.0'
      implementation 'androidx.multidex:multidex:2.0.0'
      implementation 'androidx.appcompat:appcompat:1.0.2'
  
      implementation "android.arch.navigation:navigation-fragment-ktx:$nav_version"
      implementation "android.arch.navigation:navigation-ui-ktx:$nav_version"
  
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
  }
  repositories {
      mavenCentral()
  }
  </code></pre>
  
  <p>When I try to run my code, I get below error:  </p>
  
  <blockquote>
    <p>Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
    public val Activity.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome
    public val Dialog.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome
    public val android.app.Fragment.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome
    public val androidx.fragment.app.Fragment.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome
    public val LayoutContainer.detailButton: Button! defined in kotlinx.android.synthetic.main.fragment_welcome    </p>
  </blockquote>
  
  <p>How can I resolve that error?</p>