code: @Override
      @SuppressWarnings("unchecked")
      public void renew(Map<String, String> credentials, Map topologyConf) {
          try {
              Credentials credential = getCredentials(credentials);
              if (credential != null) {
                  Configuration configuration = new Configuration();
                  Collection<Token<? extends TokenIdentifier>> tokens = credential.getAllTokens();
  
                  if(tokens != null && tokens.isEmpty() == false) {
                      for (Token token : tokens) {
                          //We need to re-login some other thread might have logged into hadoop using
                          // their credentials (e.g. AutoHBase might be also part of nimbu auto creds)
                          login(configuration);
                          long expiration = (Long) token.renew(configuration);
                          LOG.info("HDFS delegation token renewed, new expiration time {}", expiration);
                      }
                  } else {
                      LOG.debug("No tokens found for credentials, skipping renewal.");
                  }
              }
          } catch (Exception e) {
              LOG.warn("could not renew the credentials, one of the possible reason is tokens are beyond " +
                      "renewal period so attempting to get new tokens.", e);
              populateCredentials(credentials, topologyConf);
          }
      }
docs: {@inheritDoc}