void registerUnexpectedDirsForMountPath(String mountPath, int numberOfUnexpectedDir) {
    mountPathToNumberOfUnexpectedDirs.put(mountPath, numberOfUnexpectedDir);
  }
Register number of unexpected directories with the given mount path.
@param mountPath The mount path
@param numberOfUnexpectedDir The number of unexpected directories
ambry-store/src/main/java/com/github/ambry/store/StorageManagerMetrics.java