This object property is a shortcut for the original gr:includesObject property for the common case of having exactly one single gr:ProductOrService instance included in an Offering.
When linking to an instance of gr:SomeItems or gr:Individual, it is equivalent to using a gr:TypeAndQuantityNode with gr:hasUnitOfMeasurement="C62"^^xsd:string and gr:amountOfThisGood="1.0"^^xsd:float for that good.
When linking to a gr:ProductOrServiceModel, it is equivalent to
1. defining an blank node for a gr:SomeItems
2. linking that blank node via gr:hasMakeAndModel to the gr:ProductOrServiceModel, and
3. linking from the gr:Offering to that blank node using another blank node of type gr:TypeAndQuantityNode with gr:hasUnitOfMeasurement="C62"^^xsd:string and gr:amountOfThisGood="1.0"^^xsd:float for that good.