code: public static String upperCase(String str) {
          if(isNullOrEmpty(str)) {
              return str;
          }
          return str.toUpperCase(LOCALE_ENGLISH);
      }
docs: Converts a given String to upper case with Locale.ENGLISH
  
  @param str the string to be converted to upper case
  @return the upper case of string, or itself if string is null/empty