val hashMap : collection.immutable.HashMap[State,State] = transition
val key : State = currentState
if (! hashMap.contains(key))
   hashMap.keySet.map { entry : State =>
      if (entry.ID == key.ID) {
        println("================================")
        println("entry.ID is " + entry.ID)
        println("entry == key is " + (entry == key))
        println("entry.equals(key) is " + entry.equals(key))
        println("entry eq key is " + entry.eq(key))
        println("entry.hashCode == key.hashCode is " + (entry.hashCode == key.hashCode))
        println("hashMap.contains(key) is " + hashMap.contains(key))
        System.exit(0)
      }
    }
else
  println(s"""Key "${key.ID}" found""")

Key "Start" found
Key "Start" found
Key "Start" found
================================
entry.ID is Start
entry == key is true
entry.equals(key) is true
entry eq key is true
entry.hashCode == key.hashCode is true
hashMap.contains(key) is false