code: public void resetHeader(LogFileHandle validFile)
      {
          if (tc.isEntryEnabled())
              Tr.entry(tc, "resetHeader");
          _logFileHeader.resetHeader(validFile.logFileHeader());
          if (tc.isEntryEnabled())
              Tr.exit(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.