Long timestampMsSinceEpoch; if (Strings.isNullOrEmpty(timestampAttribute)) { timestampMsSinceEpoch = asMsSinceEpoch(pubsubTimestamp); checkArgument( timestampMsSinceEpoch != null, "PubSub message is missing a value for timestamp attribute %s", timestampAttribute); timestampMsSinceEpoch = asMsSinceEpoch(value); checkArgument( timestampMsSinceEpoch != null,