private static void sleepRandomAmount() {
    int waitTimeMillis = (int) (Math.random() * MAX_WAIT_TIME_MILLISECONDS_BEFORE_RETRY);
    try {
      Thread.sleep(waitTimeMillis);
    } catch (InterruptedException ex) {
      // Ignored.
    }
  }
An {@link Aead} that does AES-GCM encryption with a key stored in <a
href="https://developer.android.com/training/articles/keystore.html">Android Keystore</a>.

<p>This class requires Android M (API level 23) or newer.

@since 1.0.0
java_src/src/main/java/com/google/crypto/tink/integration/android/AndroidKeystoreAesGcm.java