func (c *Connector) SessionVariables() SessionVariables {
	c.mu.RLock()
	defer c.mu.RUnlock()
	return c.sessionVariables
}
func (c *Connector) SessionVariables() SessionVariables {
	c.mu.RLock()
	defer c.mu.RUnlock()
	return c.sessionVariables
}
// SessionVariables returns the session variables stored in connector.