Rest API - How to Update Worker Assignment including EFF or DFF

In the Oracle documentation on page:

https://docs.oracle.com/en/cloud/saas/human-resources/23d/farws/op-workers-workersuniqid-child-workrelationships-periodofserviceid-child-assignments-assignmentsuniqid-patch.html

The request body - application/json (schema) shows that the assignmentsEFF: field is an array --> object --> object --> array --> object.

From the documentation, I don't understand how to write the discriminator. I have tried several variations of the request body below using SOAP UI. Can someone help me get the request correct so it works?

Thx.

Worker Assignment Update:

URL: /hcmRestApi/resources/11.13.18.05/workers/300000133749200%2C2023-12-04/child/workRelationships/300000133735872/child/assignments/300000133735886%2C2023-12-04

Request Header:

effective-Of RangeStartDate=2023-12-02;RangeMode=UPDATE