code: public void lockLocation() throws IllegalStateException {
  		checkState(lockedLocation == null, "Location is already locked");
  		checkState(sharedSlot != null, "Cannot lock location without a slot.");
  
  		lockedLocation = sharedSlot.getTaskManagerLocation();
  	}
docs: Locks the location of this slot. The location can be locked only once
  and only after a shared slot has been assigned.
  
  @throws IllegalStateException Thrown, if the location is already locked,
  or is no slot has been set, yet.