In order to display property the Data Object in the process editor, it requires two images: the icon and the shape. BPMN images should follow the spec as well.

Because the Data Object icon will be placed on the palette in a new category called "Artifacts", we will need to create an icon to represent this new category.

As for the content of an icon to represent artifacts, the BPMN 2.0 specification is fairly vague: " A new shape representing a kind of Artifact MAY be added to a Diagram, but the new Artifact shape SHALL NOT conflict with the shape specified for any other BPMN element or marker."