Minor optimization: TrailingEntityMapSupport.getTrailingEntity(PlanningVariableDescriptor,Object) creates new iterator

TrailingEntityMapSupport#getTrailingEntity(PlanningVariableDescriptor,Object)
Creates a new iterator for each call to just retrieve the first object using next()

Wouldn't a more efficient data structure instead of Map<Object, Set<Object>> be faster and produce less garbage? (a list or a single object as value, especially because if the set has size()>1 throws exception anyway)