I have created a new data entity and add the following method on it. Now we would like to test this with a JSON script in Postman

The idea is to send a JSON script to this method from Postman (which should do a update in D365). As you can see the method has parameters, and that seems a problem for Postman. If I create a D365 entity method without parameters, it works fine, but I need parameters. The following message (in Postman) occurs:
I already try out the following scripts (Post requests), but none of them were successful. Does anyone of yours any clue if it is possible to add parameters?
1. POST /{url}/data/entityname(dataAreaId='usmf',ProjId='000002')/Microsoft.Dynamics.DataEntities.Test
Body:
{
"dataAreaId" : "usmf",
"ProjID" : "000002"
}
2. POST /{url}/data/entityname/Microsoft.Dynamics.DataEntities.Test(dataAreaId='usmf',ProjId='000002')
Body:
{
"dataAreaId" : "usmf",
"ProjID" : "000002"
}
3. POST /{url}/data/entityname/Microsoft.Dynamics.DataEntities.Test
Body:
{
"dataAreaId" : "usmf",
"ProjID" : "000002"
}
4. POST /{url}/data/entityname/Microsoft.Dynamics.DataEntities.Test
+ insert parameters in the 'Params' section.
