Summary:
We currently have E016 for ADDED trips:
https://github.com/CUTR-at-USF/gtfs-realtime-validator/blob/master/RULES.md#E016
ADDED has recently been marked as "unspecified" in GTFS-realtime, which means that the exact behavior isn't defined:
google/transit#230
We should probably remove this error, as some producers could consider this case valid, and instead add a warning that ADDED trips are unspecified and behavior of consumers isn't consistent.
Steps to reproduce:
Run the validator
Expected behavior:
Don't throw errors on unspecified behavior
Observed behavior:
ADDED is now unspecified in GTFS-RT, but we throw errors on it based on our past assumption of how it works (which, it turns out, others disagree with - google/transit#230).