title: NoClassDefFoundError on executing AsyncTask
body: <p>I have an AsyncTask in my android app. That works fine for android 19 (or later), but when i try to run app and execute this asynctask in android 15, returned this exception:</p>
  
  <pre><code>9692-10041/com.test.debug E/ACRA﹕ com.test.debug fatal error : java.util.Objects[]
  java.lang.NoClassDefFoundError: java.util.Objects[]
          at com.test.ContentActivity.startContentTask(ContentActivity.java:181)
          at com.test.ContentActivity.onCreate(ContentActivity.java:161)
          at android.app.Activity.performCreate(Activity.java:4645)
          at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1051)
          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1940)
          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2001)
          at android.app.ActivityThread.access$600(ActivityThread.java:129)
          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1153)
          at android.os.Handler.dispatchMessage(Handler.java:99)
          at android.os.Looper.loop(Looper.java:137)
          at android.app.ActivityThread.main(ActivityThread.java:4516)
          at java.lang.reflect.Method.invokeNative(Native Method)
          at java.lang.reflect.Method.invoke(Method.java:511)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
          at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>I added <code>compile 'com.android.support:support-v4:21.0.3'</code> in build.gradle.</p>
  
  <p>(In this AsyncTask, I'm using HttpClient and called a web service)</p>