@Override
  public int compareTo(CallSiteId o) {
    return Unsigned.compare(offset, o.offset);
  }
A call_site_id_item: https://source.android.com/devices/tech/dalvik/dex-format#call-site-id-item
android/android_framework/dex-maker/src/main/java/com/android/dex/CallSiteId.java