Not able to fetch service request due date in groovy

Summary:

We are using milestones to calculate the due date on the Service request, this calculation is oracle behavior and we do not have any visibility about where it is being performed.

We have Due date field (OOTB) in service request object which is formula field and so we can are not able to fetch the due date inside application composer while writing the groovy. We have a requirement from business, where, when a due date is updated on the SR, update the same due date on all the Work Orders associated with the SR. As we can not fetch the due date field in application composer we tried to do the GET API call on service request, read the due date from it and then use the due date to set