The workstream the actual is for. Omitting this field matches an actual on any workstream and leaves that actual's workstream unchanged. null matches only an actual that has no workstream, and ignores actuals with workstreams in its filter. A value matches only an actual on that workstream, and ignores actuals on every other workstream. workstreamId will not update the existing actual's workstream. If nothing matches, the actual is created on the workstream you sent, or with no workstream when the field is omitted or null, in which case it appears under No Workstream. Where two or more actuals exist for the same date, project, person, and role on different workstreams, omitting this field updates the oldest of them. Send workstreamId on every request if the project uses workstreams.
