@startuml
hide empty members
hide circle
top to bottom direction

' Define the objects in the diagram
class "bus" as B

class "connection1" as C1
class "connection2" as C2

class "topic-handler1" as TH1
class "topic-handler2" as TH2

' Define the class relationships
B *-- C1
B *-- C2

C1 *-- TH1
C2 *-- TH2
@enduml