code: public void lockLocation(TaskManagerLocation taskManagerLocation) {
  		checkNotNull(taskManagerLocation);
  		checkState(lockedLocation == null, "Location is already locked.");
  
  		lockedLocation = taskManagerLocation;
  	}
docs: Locks the location of this slot. The location can be locked only once
  and only after a shared slot has been assigned.
  
  <p>Note: This method exists for compatibility reasons with the new {@link SlotPool}.
  
  @param taskManagerLocation to lock this co-location constraint to