When is GenericIndexed V2 constructed?

[Hao Luo]

Hi,
    I have a few questions regarding the V2.

   1. When is it constructed from values? The fromArray() or fromIterable()
   seems always create version 1 and createGenericIndexedVersionTwo only loads
   existing V2 GenericIndexed.
   2. What is the purpose of GenericIndexed V2? When is it used?

Thanks.
Hao Luo