I noticed this while working on change
I49ffebcd129990f1835f404d98b51732a32171eb and I realized
the scheduler_hints in the legacy filter_properties
dict is a bit different than what's in the RequestSpec
object, namely that the request validation schema is
per-hint. Some require a single value, like 'group', and
some accept a list of values, like 'different_host'.
Given how nebulous scheduler hints are, we should probably
note these in the API reference for the parameter, especially
because scheduler hints should not be considered interoperable.
Change-Id: I74114fc56bee2bebf4a5f5d6823ec968cad9a8e9
a6fcfb28ae