code: public FilterCell findNextCell(int nextValue) {
          if (nextCell == null) {
              return null;
          }
          return (FilterCell) (nextCell.get(nextValue));
      }
docs: Find the next cell, for a given number, which may come after this cell
  in the address tree.
  
  @param nextValue
  The next value in the IPv6 Address that is to be tested
  for inclusion in the address tree
  @return null if the the nextValue does not have another cell connected to
  this
  cell in the tree. Otherwise return the next cell in the tree that
  is represented
  by the nextValue.