REST API to update negotiation open date

Summary:

Can we update the negotiation open date using API?

We trying to update negotiation open date for case when the approver approved negotiation later that negotiation open data. In this case the negotiation status will be Approved (Not Published).
In UI, user can update the open date by navigating to the negotiation > action > Modify Schedule and change the open date to future date, after that user need to Publish the negotiation.
We want to do this activity (Modify open date and publish) through API.
We tried use "Update one negotiation" rest API to update the open date but it's got this error: