title: BottomSheetBehavior not in androidX libraries
body: <p>I was using the <code>BottomSheetBehavior</code> with the original support library:</p>
  
  <pre><code>implementation 'com.android.support:design:27.1.1' 
  </code></pre>
  
  <p>When I migrated to use the new <code>androidx</code> libraries though the <code>BottomSheetBehavior</code> is missing. The mapping from the above support library isn't in the <a href="https://developer.android.com/topic/libraries/support-library/refactor" rel="noreferrer">AndroidX Refactoring List</a> either, but the migration tool removed it.</p>
  
  <p>What am I missing to include the BottomSheetBehavior with the new <code>androidx</code> libraries.</p>
  
  <pre><code>dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'com.google.android.material:material:1.0.0-beta01'
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
  
      // ReactiveX
      implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
      implementation 'io.reactivex.rxjava2:rxkotlin:2.2.0'
  
      implementation 'com.android.support:design:28.1.0'
  
      // Android Compatability Libraries
      // Version: https://developer.android.com/topic/libraries/support-library/refactor
      implementation 'androidx.appcompat:appcompat:1.0.0-beta01'
      implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha1'
      implementation 'androidx.legacy:legacy-support-v4:1.0.0-beta01'
      implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0-beta01'
      implementation 'androidx.recyclerview:recyclerview:1.0.0-beta01'
  
      // Android Navigation Component
      // Check here for updated version info - will move to androidx soon.
      // https://developer.android.com/topic/libraries/architecture/adding-components
      def nav_version = "1.0.0-alpha04"
  
      // use -ktx for Kotlin
      implementation "android.arch.navigation:navigation-fragment-ktx:$nav_version"
      implementation "android.arch.navigation:navigation-ui-ktx:$nav_version"
      androidTestImplementation "android.arch.navigation:navigation-testing-ktx:$nav_version"
  
      // Testing
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
  }
  </code></pre>