Set the request header Content-Type to application/json.
This is the Property Code, and not the Display Name that you see on most screens, that the request will update the value for. To copy the Property Code to your clipboard click on the clipboard iconto the right of any property.
This is the new value that will be assigned to the respective property.
This is a required, boolean value indicating whether or not the value is an expression (true) or a literal value. On the FlexDeploy screens the properties have a button that toggles to indicate whether a value is an expression or a literal value .