All the timestamps in the JSON we receive are UTC, but the TA ignores the time zone in the ISO 8601 string, so it defaults to local time. Thus, all our events are timestamped several hours into the future.
I noticed that the timestamps Google provides vary from millisecond to nanosecond precision, but trailing zeros are truncated before the "Z" is tacked on. This makes it difficult to specify a time format with a trailing time zone that will work for every event. But instead, shouldn't all the source types have TZ = UTC in props?