Set SAC status to false when connection is lost

Setting the SAC status to false is safe when the connection
is lost, even if no notification came. This makes sure
the consumer instance state is consistent, as a new SAC consumer
is always inactive when it first registers.

References #46

Author: acogoluegnes

src/main/java/com/rabbitmq/stream/impl/StreamConsumer.java

@@ -445,6 +445,10 @@ synchronized void setTrackingClient(Client client) {
 
   void setSubscriptionClient(Client client) {
     this.subscriptionClient = client;
+    if (client == null && this.isSac()) {
+      // we lost the connection
+      this.sacActive = false;
+    }
   }
 
   synchronized void unavailable() {