title: androidx with databinding error: package android.support.constraint does not exist
body: <p>I'm just learning about <code>databinding</code> and tried to use the new library structure as <code>androidx</code>.
  When I tried to build the project I'm facing this error.</p>
  
  <blockquote>
    <p>error: package android.support.constraint does not exist</p>
  </blockquote>
  
  <p>This error is in the Binding generated file as </p>
  
  <pre><code>public class ActivityMainBindingImpl extends ActivityMainBinding  {
      @Nullable
      private static final androidx.databinding.ViewDataBinding.IncludedLayouts sIncludes;
      @Nullable
      private static final android.util.SparseIntArray sViewsWithIds;
      static {
          sIncludes = null;
          sViewsWithIds = null;
      }
      // views
      @NonNull
      private final android.support.constraint.ConstraintLayout mboundView0;
      @NonNull
      private final android.widget.TextView mboundView1;
  </code></pre>
  
  <p>Here is my <code>build.gradle</code> app module.</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  apply plugin: 'kotlin-android'
  
  apply plugin: 'kotlin-android-extensions'
  
  android {
      compileSdkVersion 28
      defaultConfig {
          applicationId "com.climesoft.learn.livedatabinding"
          minSdkVersion 19
          targetSdkVersion 28
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
      dataBinding {
          enabled = true
      }
  }
  
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
      implementation 'androidx.appcompat:appcompat:1.0.2'
      implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test:runner:1.1.0'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'
  }
  </code></pre>
  
  <p>Here is <code>build.gradle</code> project module.</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      ext.kotlin_version = '1.3.10'
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.2.1'
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>And the final <code>gradle.properties</code> file is this.</p>
  
  <pre><code># Project-wide Gradle settings.
  # IDE (e.g. Android Studio) users:
  # Gradle settings configured through the IDE *will override*
  # any settings specified in this file.
  # For more details on how to configure your build environment visit
  # http://www.gradle.org/docs/current/userguide/build_environment.html
  # Specifies the JVM arguments used for the daemon process.
  # The setting is particularly useful for tweaking memory settings.
  org.gradle.jvmargs=-Xmx1536m
  # When configured, Gradle will run in incubating parallel mode.
  # This option should only be used with decoupled projects. More details, visit
  # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
  # org.gradle.parallel=true
  # Kotlin code style for this project: "official" or "obsolete":
  kotlin.code.style=official
  
  android.useAndroidX=true
  
  android.enableJetifier=true
  </code></pre>
  
  <p>So why android studio not generating the Binding class with <code>androidx.constraintlayout</code> package?</p>