public int descriptorIndexFromTypeIndex(int typeIndex) {
    checkBounds(typeIndex, tableOfContents.typeIds.size);
    int position = tableOfContents.typeIds.off + (SizeOf.TYPE_ID_ITEM * typeIndex);
    return data.getInt(position);
  }
Look up a descriptor index from a type index. Cheaper than: {@code
open(tableOfContents.typeIds.off + (index * SizeOf.TYPE_ID_ITEM)).readInt();}
android/android_framework/dex-maker/src/main/java/com/android/dex/Dex.java