code: @Nullable
    public static XMLGregorianCalendar getXMLCalendarTime (@Nullable final GregorianCalendar aBase)
    {
      if (aBase == null)
        return null;
      return s_aDTFactory.newXMLGregorianCalendarTime (aBase.get (Calendar.HOUR_OF_DAY),
                                                       aBase.get (Calendar.MINUTE),
                                                       aBase.get (Calendar.SECOND),
                                                       aBase.get (Calendar.MILLISECOND),
                                                       getTimezoneOffsetInMinutes (aBase));
    }
docs: Get the passed object as {@link XMLGregorianCalendar} time (without a
  date).
  
  @param aBase
  The source object. May be <code>null</code>.
  @return <code>null</code> if the parameter is <code>null</code>.