code: private static String indexExpressionsToString(List<IndexExpression> indexExpressions) throws IOException
      {
          assert indexExpressions != null;
          // oh, you thought cfdefToString was awful?
          IndexClause indexClause = new IndexClause();
          indexClause.setExpressions(indexExpressions);
          indexClause.setStart_key("".getBytes());
          TSerializer serializer = new TSerializer(new TBinaryProtocol.Factory());
          try
          {
              return Hex.bytesToHex(serializer.serialize(indexClause));
          }
          catch (TException e)
          {
              throw new IOException(e);
          }
      }
docs: convert a list of index expression to string