static Collection<Account> deserializeAccounts(byte[] bytes) {
    try {
      Collection<Account> accounts = objectMapper.readValue(bytes, new TypeReference<Collection<Account>>() {
      });
      return accounts;
    } catch (IOException e) {
      logger.error("Failed to deserialized bytes to account collection: {}", e.getMessage());
      return null;
    }
  }
Deserialize the given byte array to an account collection.
It returns null at any exception. This function assume the bytes are in json format.
@param bytes The byte array to deserialize.
@return The {@link Collection} of {@link Account}s.
ambry-account/src/main/java/com/github/ambry/account/BackupFileManager.java