How to test for null in service mapping expression

Summary:

We have a requirement to price based on requested ship date or requested arrival date. The examples shown in several support notes includes statements like this: "If customers want to use any other Order level dates in place of OrderedDate eg. RequestShipDate or RequestArrivalDate, please replace the View Object Attribute references to OrderedDate above with RequestShipDate or RequestArrivalDate".

In our environment, orders may be either so our need is to use an Expression instead of just View Object Attribute, something like RequestShipDate is null ? RequestArrivalDate : RequestShipDate. Is that the correct syntax?

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