SAP RAP: Modify ENTITIES in the respond (Unmanaged Implementation)

Hello Guys,

I am working on a RAP Service type: “Unmanaged Implementation”

And I would like to modify the ENTITIES values in the respond. Below my POSTMAN request, when I execute it (POST), I want to fill the parameter: “RESERVATION” in the RESPOND.

Here my Service Exposition and Method:

Here my Business Definition:

Here my CDS:

Here my Behavior Class:

I added the code:

And when I execute the request, i have an issue:

 

It’s normal because ENTITIES is defined as IMPORTING parameter.

How can I do specify ENTITIES as CHANGING ?

Any idea?

Best regards,

Rachid