How to get the UniqId to pass it as a parameter in OIC

How to get this UniqId and pass it to the URI

e.g., we need the gradeUniqId to pass it to the following endpoint: /hcmRestApi/resources/11.13.18.05/grades/{gradesUniqID}/child/GradeCustomerFlex.

PS: I just clicked the hyperlink in Postman to get it after running the basic grade data "/hcmRestApi/resources/11.13.18.05/grades", but I need the way to do it in OIC.