title: Error adding library Room Persistence
body: <p>I'm starting to work with room persistence</p>
  
  <p>I added the room in the gradle and the error below appeared:    </p>
  
  <blockquote>
    <p>Error:Failed to resolve: annotationProcessor<br>
      href="openFile:C:/.../app/build.gradle">Open File</p>
  </blockquote>
  
  <p>This error appears when I synchronize the gradle</p>
  
  <p>How can I resolve this issue?</p>
  
  <p>This is the gradle project:</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      repositories {
          jcenter()
  
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:2.3.1'
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          jcenter()
          maven { url 'https://maven.google.com' }
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>app gradle:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 25
      buildToolsVersion "25.0.0"
      dataBinding {
          enabled = true
      }
      defaultConfig {
          applicationId "com.app.bob.app"
          minSdkVersion 22
          targetSdkVersion 25
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })
      compile 'com.android.support:appcompat-v7:25.3.0'
      compile 'com.android.support:support-annotations:25.3.0'
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
      compile 'com.squareup.retrofit2:retrofit:2.3.0'
      compile 'com.google.code.gson:gson:2.8.0'
      compile 'com.squareup.retrofit2:converter-gson:2.3.0'
      compile 'com.android.support:support-v4:25.3.0'
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:recyclerview-v7:25.3.0'
      compile 'com.squareup.picasso:picasso:2.5.2'
      compile 'com.jakewharton:butterknife:8.7.0'
      annotationProcessor 'com.jakewharton:butterknife-compiler:8.7.0'
      compile 'com.android.support:cardview-v7:25.3.0'
      compile 'android.arch.persistence.room:runtime: 1.0.0-alpha5'
      annotationProcessor 'android.arch.persistence.room:compiler: 1.0.0-alpha5'
      compile 'android.arch.lifecycle:runtime:1.0.0-alpha5'
      compile 'android.arch.lifecycle:extensions:1.0.0-alpha5'
      annotationProcessor 'android.arch.lifecycle:compiler:1.0.0-alpha5'
      testCompile 'android.arch.persistence.room:testing:1.0.0-alpha5'
      compile 'android.arch.persistence.room:rxjava2:1.0.0-alpha5'
  }
  </code></pre>