code: public long getLongField(String name) throws NumberFormatException {
          HttpField field = getField(name);
          return field == null ? -1L : field.getLongValue();
      }
docs: Get a header as an long value. Returns the value of an integer field or
  -1 if not found. The case of the field name is ignored.
  
  @param name the case-insensitive field name
  @return the value of the field as a long
  @throws NumberFormatException If bad long found