docs: public long getDateHeader(String name)
    {
      if (_header != null)
      {
        long longVal = _header.getDateHeader(name);
        if (longVal != -1)
        {
          return longVal;
        }
      }
      if (this.headerTable != null)
      {
        int i = 0;
        for (Object obj : headerTable[0])
        {
          String strVal = (String) obj;
          if (name.equals(strVal))
          {
            try
            {
              return Long.valueOf((String) headerTable[1].get(i));
            }
            catch (NumberFormatException nfe)
            {
              throw new IllegalArgumentException(nfe);
            }
          }
          i++;
        }
      }
      return -1;
    }