code: protected String join(List<String> values)
      {
          StringBuilder sb = new StringBuilder(100);
          if(values.size() == 0)
              return sb.toString();
  
          sb.append(values.get(0));
  
          if(values.size() == 1)
              return sb.toString();
  
          for (int i = 1; i < values.size(); i++)
          {
              sb.append(",").append(values.get(i));
          }
  
          return sb.toString();
      }
docs: Joing the values together in a comma separated list
  @param values The values to join
  @return The combined values