code: String regExpGroupName(String elementName) {
          for (String regexp : sortedRegExpList) {
              if (elementName.startsWith(regexp)) {
                  return regExpGroupMap.get(regexp);
              }
          }
          return null;
      }
docs: Search for element name in the sorted regular expression
  list, if found return the group name.  If not, return null.
  
  @param elementName Name of element to be found in the regular
  expression list.