code: public static String setPrefix(String text, String prefix)
    {
      if(text == null) {
        return null;
      }
      if(!text.startsWith(prefix)) {
        text = prefix + text;
      }
      return text;
    }
docs: Ensure a given text start with requested prefix. If <code>text</code> argument is empty returns given prefix;
  returns null if <code>text</code> argument is null.
  
  @param text text to add prefix to, null accepted,
  @param prefix prefix to force on text start.
  @return prefixed text or null.