code: public void resetHeader(LogFileHeader validHeader)
      {
          if (tc.isEntryEnabled())
              Tr.entry(tc, "resetHeader", this);
          _date = 0;
          _firstRecordSequenceNumber = 0;
          _serverName = validHeader.serverName();
          _serviceName = validHeader.serviceName();
          _logName = validHeader.logName();
          _variableFieldData = initVariableFieldData();
          _serviceData = null;
          if (tc.isEntryEnabled())
              Tr.entry(tc, "resetHeader");
      }
docs: Ensure that the internal state of a header if valid, by copying a known
  good header to an invalid header. This method is called during the initialization
  and validation of a pair of recovery log files.