Include time zone in event timestamp for Spanner implementation

Google Cloud Spanner adds seven hours to java.sql.Timestamp objects
when converting to UTC, resulting in entries being timestamped as
occurring in the future.

I believe this is related to their treatment of Timestamp literals,
which assume a default time zone of America/Los_Angeles:
https://cloud.google.com/spanner/docs/reference/standard-sql/lexical#timestamp_literals

Using Instant includes the time zone in the String which keeps the
timestamp accurate in Spanner.

Change-Id: I313af4fbd7803478fb0604913ee2d781de37c895
1 file changed