public TopicSubscriptionObserver(
            [NotNull] IMessageNameFormatter formatter,
            [NotNull] AzureServiceBusInboundTransport inboundTransport)
        {
            if (formatter == null)
                throw new ArgumentNullException("formatter");
            if (inboundTransport == null)
                throw new ArgumentNullException("inboundTransport");

            _formatter = formatter;
            _inboundTransport = inboundTransport;

            _bindings = new Dictionary<Guid, TopicDescription>();
        }
        public TopicSubscriptionObserver(
            [NotNull] IMessageNameFormatter formatter,
            [NotNull] AzureServiceBusInboundTransport inboundTransport)
        {
            if (formatter == null)
            {
                throw new ArgumentNullException("formatter");
            }
            if (inboundTransport == null)
            {
                throw new ArgumentNullException("inboundTransport");
            }

            _formatter        = formatter;
            _inboundTransport = inboundTransport;

            _bindings = new Dictionary <Guid, TopicDescription>();
        }