PlantUML source code.

@startuml
class ColliderLibrary
{
 + {static} string CollideWith(Asteroid x, Asteroid y)
 + {static} string CollideWith(Asteroid x, Spaceship y)
 + {static} string CollideWith(Spaceship x, Asteroid y)
 + {static} string CollideWith(Spaceship x, Spaceship y)
}
abstract class SpaceObject << (R,lightgreen) >>
{
 + int Size
}
class Asteroid << (R,lightgreen) >> extends SpaceObject
{
 + «Create» Asteroid()
}
class Spaceship << (R,lightgreen) >> extends SpaceObject
{
 + «Create» Spaceship()
}
@enduml