question: void placeAtPosition ( final IGroupMemberNode node , final Integer positionToPlace ) { if ( positionToPlace == null ) { nonOptionalNonMinusNodes . addLast ( node ) ; } else { nonOptionalNonMinusNodes . add ( positionToPlace , node ) ; } }
target:  Places the node at the specified position in the list of non-optional non-minus nodes. If the position is null, the node is added at the end (this is, right in front of the bordering optional or minus node).