Rectangular Object Node in Activity Diagram

Question

Can anyone tell me how to design UML's Object Node in PlantUml ? According to the UML's v2.5 spec (section 15.2.4), Object Nodes are supposed to be square, while the regular and most used Action Nodes are squircles.

All I can find in the PlantUml documentation is how to display all the Action Nodes octagon ...

I'm working with the PlantUml's v1 activity grammar :

@startuml
(*) --> "First Action Node"
--> "HERE I WANT AN OBJECT NODE"
--> "Last Action Node"
--> (*)
@enduml

Answer 1

I think this is only achievable with the new Activity diagram syntax (still beta), in which you can do:

@startuml
start
:First Action Node;
:HERE I WANT AN OBJECT NODE]
:Last Action Node;
stop
@enduml

Result: