Hi R., and all,
You must use class, entity, or... name with together, as:
@startuml
class RuEventType {
field a
}
together {
class RuEventType
class ConnectArgs
class RuStateType
}
legend
NOTE: Added elements are in <back:Chartreuse>Green
end legend
@enduml
If that can help,
Regards,
Th.