Steps to reproduce:


- Do Reverse Engineering of 'void test()'  method from
  'Test' class and create a Sequence diagram:
  ---------------------------------------------------------------     
  public class Test {
    enum DAY {
        SUNDAY,
        MONDAY,
        TUESDAY,
        WEDNESDAY,
        THURSDAY,
        FRIDAY,
        SATURDAY
    }
    
    public void test(){
        
        int n = 20;
        String name = "";
        DAY day = DAY.MONDAY;
        
        switch(day){
            case SUNDAY:  name = day.toString();
            switch(n){
                case 0:  day = DAY.SUNDAY;
                case 1:  day = DAY.MONDAY; break;
                default: day = DAY.TUESDAY;
            }
            
            case MONDAY:  name = day.name();
            switch(n){
                case 2:  day = DAY.TUESDAY;
                case 3:  day = DAY.MONDAY; break;
                default: day = DAY.SUNDAY;
            }
            break;
            default:  name = day.getClass().getName();
        }
    }      
  }

  ---------------------------------------------------------------     

  The outer Combined fragment has 3 interaction operands on the Sequence 
  diagram.
  The fist operand has '[n]' expression  instead of '[ day = SUNDAY ]'.
  The second operand has '[n]' expression  instead of '[ day = MONDAY ]'.