@Override
  public void close() throws SQLException {
      try {
        if (!isClosed) {
          TCloseSessionReq closeReq = new TCloseSessionReq(sessHandle);
          client.CloseSession(closeReq);
        }
      } catch (TException e) {
        throw new SQLException("Error while cleaning up the server resources", e);
      } finally {
        isClosed = true;
        client = null;
        if (transport != null && transport.isOpen()) {
          transport.close();
          transport = null;
        }
      }
  }
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