public void renewDelegationToken(String tokenStr) throws SQLException {
    if (isClosed) {
      throw new SQLException("Connection is closed");
    }
    TRenewDelegationTokenReq cancelReq = new TRenewDelegationTokenReq(sessHandle, tokenStr);
    try {
      TRenewDelegationTokenResp renewResp =
          client.RenewDelegationToken(cancelReq);
      Utils.verifySuccess(renewResp.getStatus());
      return;
    } catch (TException e) {
      throw new SQLException("Could not renew token: " +
          e.getMessage(), " 08S01", e);
    }
  }
Lookup varName in sessConfMap, if its null or empty return the default
value varDefault
@param varName
@param varDefault
@return
jdbc/src/java/org/apache/hive/jdbc/HiveConnection.java