code: private String getWindowString(TimeWindow window, boolean includeDays) {
          StringBuilder str = new StringBuilder();
          if( includeDays ) {
              if( window.getStartDayOfWeek() == null ) {
                  str.append("*");
              }
              else {
                  str.append(window.getStartDayOfWeek().getShortString());
              }
              str.append(":");
          }
          str.append(String.format("%02d:%02d", window.getStartHour(), window.getStartMinute()));
          str.append("-");
          if( includeDays ) {
              if( window.getEndDayOfWeek() == null ) {
                  str.append("*");
              }
              else {
                  str.append(window.getEndDayOfWeek().getShortString());
              }
              str.append(":");
          }
          str.append(String.format("%02d:%02d", window.getEndHour(), window.getEndMinute()));
          return str.toString();
      }
docs: Formats a time window as hh24:mi-hh24:mi or ddd:hh24:mi-ddd:hh24:mi
  @param window
  @param includeDays must be false for PreferredBackupWindow parameter
  @return formatted time window text representation