title: Android Room Persistence Library not working inside library project
body: <p>I'm developing an Android library, and want to use the new Android Room persistence library inside it. However, when launching I got this error :</p>
  <pre><code>Caused by: java.lang.RuntimeException: cannot find implementation for
  MyLibraryName.Database.QSDatabase. QSDatabase_Impl does not exist
  at android.arch.persistence.room.Room.getGeneratedImplementation(Room.java:90)
  </code></pre>
  <p>which means that the <strong>annotationProcessor</strong> is not generating the extra code during compilation.</p>
  <p>Btw, everything is working fine when I put my <em>@Database</em> code inside the app module.</p>
  <p>My gradle file (library module) :</p>
  <pre><code>apply plugin: 'com.android.library'
  apply plugin: 'groovyx.android'
  
  buildscript {
  repositories {
      jcenter()
      maven { url 'https://maven.google.com' }
  }
  
  dependencies {
      classpath 'com.android.tools.build:gradle:2.3.2'
      classpath 'org.codehaus.groovy:groovy-android-gradle-plugin:1.1.0'
  }
  }
  
  android {
  compileSdkVersion 25
  buildToolsVersion &quot;25.0.3&quot;
  
  defaultConfig {
      minSdkVersion 15
      targetSdkVersion 25
      versionCode 1
      versionName &quot;1.0&quot;
      configurations.all {
      resolutionStrategy.eachDependency { DependencyResolveDetails details -&gt;
              def requested = details.requested
              if (requested.group == 'com.android.support') {
                  if (!requested.name.startsWith(&quot;multidex&quot;)) {
                      details.useVersion '25.3.0'
                  }
              }
          }
      }
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  sourceSets { main { java.srcDirs = ['src/main/java', 'src/main/groovy'] } }
  }
  
  dependencies {
  // google Room persistence library
  compile &quot;android.arch.persistence.room:runtime:1.0.0-alpha1&quot;
  annotationProcessor &quot;android.arch.persistence.room:compiler:1.0.0-alpha1&quot;
  compile fileTree(include: ['*.jar'], dir: 'libs')
  androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', 
  {
      exclude group: 'com.android.support', module: 'support-annotations'
  })
  // google location service
  compile 'com.google.android.gms:play-services-location:10.2.4'
  androidTestCompile 'junit:junit:4.12'
  // Http
  compile 'com.squareup.retrofit2:retrofit:2.3.0'
  compile 'com.google.code.gson:gson:2.6.2'
  compile 'com.squareup.retrofit2:converter-gson:2.3.0'
  compile 'com.squareup.okhttp3:logging-interceptor:3.8.0'
  compile 'com.squareup.retrofit2:converter-scalars:2.1.0'
  // groovy
  compile group: 'org.codehaus.groovy', name: 'groovy-all', version: '2.4.4'
  }
  </code></pre>