code: private List<ParseTree> filterSpaceTokens(List<ParseTree> inputArrayList) {
          List<ParseTree> ret = new ArrayList<ParseTree>(inputArrayList.size());
          for (ParseTree item : inputArrayList) {
              if (!(item instanceof TerminalNode) || ((TerminalNodeImpl) item).getSymbol().getType() != CSSLexer.S) {
                  ret.add(item);
              }
          }
          return ret;
      }
docs: remove terminal node emtpy tokens from input list
  
  @param inputArrayList original list
  @return list without terminal node type = S (space)