title: How to fix 'java.lang.NoClassDefFoundError' in Android .aar project
body: <p>I have an android <code>.aar</code> library built and I am trying to integrate it with one of the projects. When the app tries to open the initial screen of the <code>.aar</code> library where I have API call using retrofit. I am getting the below exception</p>
  
  <blockquote>
    <p>java.lang.NoClassDefFoundError: Failed resolution
    of:Lokhttp3/OkHttpClient$Builder;</p>
  </blockquote>
  
  <p>I have not obfuscated or enabled pro-guard in my <code>.aar</code> project. </p>
  
  <p>Below are my <code>.aar</code> Gradle dependencies</p>
  
  <pre><code>implementation fileTree(dir: 'libs', include: ['*.jar'])
  implementation 'com.android.support:appcompat-v7:28.0.0'
  implementation 'com.android.support:design:28.0.0'
  implementation 'com.squareup.retrofit2:retrofit:2.5.0'
  implementation 'com.squareup.okhttp3:okhttp:3.12.0'
  implementation 'com.google.code.gson:gson:2.8.5'
  implementation 'com.squareup.retrofit2:converter-gson:2.2.0'
  
  testImplementation 'junit:junit:4.12'
  androidTestImplementation 'com.android.support.test:runner:1.0.2'
  androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  </code></pre>