fix Go 1.6 reflection behavior
As of Go 1.6, it's illegal to call Interface on an unexported embedded struct field.
AFAIK we don't do this anywhere in production anyway; the only place it occurs is in the encoding tests.
As of Go 1.6, it's illegal to call Interface on an unexported embedded struct field.
AFAIK we don't do this anywhere in production anyway; the only place it occurs is in the encoding tests.