Update TestStreamPayload to use timestamp protos.

[damccorm]

Currently the timestamp fields are all int64, with no indication of whether the units are seconds, milliseconds, or microseconds.

https://github.com/apache/beam/blob/release-2.16.0/model/pipeline/src/main/proto/beam_runner_api.proto#L502

Imported from Jira BEAM-8373. Original Jira may contain additional context.
Reported by: robertwb.

[vineetg3]

Hi @damccorm , the latest version seems to have a comment mentioning that the data type is inferred in milliseconds.

 // Advances the watermark to the specified timestamp.
    message AdvanceWatermark {
      // (Required) The watermark in millisecond to advance to.
      int64 new_watermark = 1;

      // (Optional) The output watermark tag for a PCollection. If unspecified
      // or with an empty string, this will default to the Main PCollection
      // Output
      string tag = 2;
    }

Is this what this issue is expecting?

[damccorm]

Yep, looks like this can be closed - thanks!