code: public void bindToDelegationToken(Token<DelegationTokenIdentifier> token) throws IOException {
      validateAccessTokenProvider();
      boundDT = token;
      DelegationTokenIdentifier dti = extractIdentifier(token);
      logger.atInfo().log("Using delegation token %s", dti);
      // extract the credential providers.
      accessTokenProvider = tokenBinding.bindToTokenIdentifier(dti);
    }
docs: Bind to a delegation token retrieved for this filesystem. Extract the secrets from the token
  and set internal fields to the values.
  
  <ol>
  <li>{@link #boundDT} is set to {@code token}.
  <li>{@link #accessTokenProvider} is set to the credential provider(s) returned by the token
  binding.
  </ol>
  
  @param token token to decode and bind to.
  @throws IOException selection/extraction/validation failure.