Ordering of classification groups does not work

Steps to reproduce:

• deploy an OpenNMS instance
• navigate to Admin -> Manage Flow Classification, open Settings tab
• pre-defined position is set to 0, user-defined position is set to 10
• the move-icon left of user-defined is useless, you cannot move user-defined up
• there is no move icon for the pre-defined group. Why?
  -> There is no way to move the pre-defined group down. Is it intended that only user-defined groups can be ordered this way. Is the predefined group alway position 0?

Now:

• disable group pre-defined and enable group pre-defined again
• pre-defined position is now set to 1, user-defined position is set to 0
• the move-icon left of user-defined is useless, you cannot move user-defined down
  -> There is no way to move the user-defined group down. This is also weird, because I have no chance to move the pre-defined group up again.

It seems that the ordering of groups is somehow broken. Even editing an entry doesn't help because you cannot enter the required numbers you need to change the ordering.