J'utilisais BottomSheetBehavioravec la bibliothèque de support d'origine:
implementation 'com.android.support:design:27.1.1' 
Lorsque j'ai migré pour utiliser les nouvelles androidxbibliothèques bien que le BottomSheetBehaviorfichier. Le mappage de la bibliothèque de support ci-dessus ne figure pas non plus dans la liste de refactorisation AndroidX , mais l'outil de migration l'a supprimé.
Ce qui me manque pour inclure le BottomSheetBehavior avec les nouvelles androidxbibliothèques.
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'
}