private int mergeApiLevels() {
    int maxApi = -1;
    for (int i = 0; i < dexes.length; i++) {
      int dexMinApi = dexes[i].getTableOfContents().apiLevel;
      if (maxApi < dexMinApi) {
        maxApi = dexMinApi;
      }
    }
    return maxApi;
  }
minimum number of wasted bytes before it's worthwhile to compact the result
android/android_framework/dex-maker/src/main/java/com/android/dx/merge/DexMerger.java