private static String getWALNameGroupFromWALName(String name, int group) {
    Matcher matcher = WAL_FILE_NAME_PATTERN.matcher(name);
    if (matcher.matches()) {
      return matcher.group(group);
    } else {
      throw new IllegalArgumentException(name + " is not a valid wal file name");
    }
  }
Find the archived WAL file path if it is not able to locate in WALs dir.
@param path - active WAL file path
@param conf - configuration
@return archived path if exists, null - otherwise
@throws IOException exception
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/AbstractFSWALProvider.java