v4 > v6 (current) migration - storage keys are different/data mismatch

[bvanderhoof]

• I was on v4, it didn't require any config at all to specify a "key"
• I migrated to v6. I used the key "root" as specified in the examples.
• I noticed that users that downloaded my new app with v6 code had to re-login, because it did not find the cached tokens in the persist async storage.

My question is: Is there a way to match whatever key v4 data was stored under? Apparently it's not "root".