Log more info about observations
Summary:
For unknown provenance cases, we include "empty" and "static" conditions in the message. Let's add those for known provenance cases, too.
Also, let's extend "empty" into a tripartite classification: "empty", (non-empty) "list-like", and "map-like". This classification is useful for e.g. some serialization cases, where map-like darrays don't cause any problems (they'll serialize the same way as if they were dicts).
Reviewed By: ricklavoie
Differential Revision:
D21936960
fbshipit-source-id:
df1bee622d81f6ff05f1f92b4106c053560c745c