private void DeclareIdle() {
       if (_state == null || !_state.IsIdle)
       {
           Logger.Info($"Cluster idle: {_node}");
 
           _state = new IdleState(_node, this, Logger);
 
           if (_registry.CurrentLeader.Equals(_node))
           {
               _registry.DemoteLeaderOf(_node.Id);
           }
       }
   }