A set of entries to add to a local threat type’s list.
The new opaque client version token. This should be retained
by the client and passed into the next call of
ComputeThreatListDiff as ‘version_token’. A separate version
token should be stored and used for each threatList.
The soonest the client should wait before issuing any diff
request. Querying sooner is unlikely to produce a meaningful
diff. Waiting longer is acceptable considering the use case.
If this field is not set clients may update as soon as they
want.