title: Repeated Build fails "To use Coroutine features, you must add `ktx`......."
body: <p>I'm new to Kotlin and Android Studio and my current problem is this...  <br/> 
  I'm trying get the Codelabs "android-room-with-a-view-kotlin" to work and whilst fixing various build errors along the way, I think my build.gradle has become very confused!
  I corrected the last build failure at <strong>Word.kt</strong> by adding the dependency </p>
  
  <pre><code>kapt 'androidx.room:room-ktx:2.2.1'
  </code></pre>
  
  <p>The next build went a little further on to <strong>WordDao.kt</strong> but failed with the same type of error.. </p>
  
  <pre><code>WordDao.java:21: error: To use Coroutine features, you must add `ktx` artifact from Room as a dependency. androidx.room:room-ktx:&lt;version&gt;
  </code></pre>
  
  <p>I'm unable to continue because I don't know what to change in the build.gradle as I've already added that dependency?</p>
  
  <p>As I've said my file is now very confused and I would appreciate <strong><em>any</em></strong> assistance in making it more sensible. Thanks, DaveInUk</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  apply plugin: "kotlin-kapt"
  
  android {
      compileSdkVersion 28
      buildToolsVersion "29.0.2"
      defaultConfig {
          applicationId "com.example.prepopplus"
          //was minSdkVersion 15  Note Old phone is API16
          minSdkVersion 21
          targetSdkVersion 28
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
  
          packagingOptions {
              exclude "META-INF/atomicfu.kotlin_module"
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.50"
  
      implementation 'androidx.appcompat:appcompat:1.1.0'
      implementation 'androidx.core:core-ktx:1.1.0'
      implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test:runner:1.2.0'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
      kapt 'androidx.room:room-ktx:2.2.1'
      kapt "androidx.room:room-compiler:2.2.1"
      implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0-rc01'
  
      implementation 'androidx.recyclerview:recyclerview:1.0.0'
      implementation 'com.google.android.material:material:1.0.0'
      implementation 'com.android.support:appcompat-v7:28.0.0'
      kapt "android.arch.persistence.room:compiler:1.1.1"
      kapt "android.arch.lifecycle:compiler:1.1.1"
  
      implementation 'androidx.room:room-runtime:2.2.1'
  }
  </code></pre>