code: public String asTagsString()
      {
          TreeMap<Tag, Value> orderedAttributes = new TreeMap<Tag, Value>(attributes);
          StringBuilder result = new StringBuilder();
          for (Iterator<Tag> tags = orderedAttributes.keySet().iterator(); tags.hasNext(); )
          {
              Tag tag = tags.next();
              result.append(tag.tag);
              if (tags.hasNext()) result.append(",");
          }
          return result.toString();
      }
docs: Returns a string representation of the tags of this <code>Attributes</code> object,
  that can be passed to {@link #fromTags(String)} to be parsed.
  
  @return the escaped tags list string