code: private static String mapSubformat(String formatString, Map<String, String> mapping, int beginIndex,
  			int currentIndex, String escapeStart, String escapeEnd, String targetEscapeStart, String targetEscapeEnd) {
  		String subformat = formatString.substring(beginIndex, currentIndex);
  		if (subformat.equals(escapeStart) || subformat.equals(escapeEnd)) {
  			return targetEscapeStart + "(error: cannot ecape escape characters)" + targetEscapeEnd;
  		}
  		if (mapping.containsKey(subformat)) {
  			String result = mapping.get(subformat);
  			if (result==null || result.length()==0) {
  				return targetEscapeStart + "(error: " + subformat + " cannot be converted)" + targetEscapeEnd;
  			}
  			return result;
  		}
  		return subformat;
  	}
docs: Append the new mapping
  
  @param formatString
  @param mapping
  @param beginIndex
  @param currentIndex
  @param resultString
  @return