public int indexOf(CstType type) {
    if (type == null) {
      throw new NullPointerException("type == null");
    }

    return indexOf(type.getClassType());
  }
Gets the index of the given type, which must have been added to this instance.

@param type {@code non-null;} the type to look up
@return {@code >= 0;} the reference's index
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/file/TypeIdsSection.java