Possible to set _uid to have doc_values = true?

[darinhoward]

In elasticsearch version 1.7.5 is it possible to have _uid have doc_values = true ?

I've read through the github issues w/ out a clear understanding if this is not on by default or not possible.

[JKhondhu (Jymit Singh Khondhu)]

https://www.elastic.co/guide/en/elasticsearch/guide/1.x/doc-values.html#_enabling_doc_values