AdvisoryConsumer not sending back acks correctly leading to stall in receiving new advisory messages. 
Fixes [AMQNET-AMQNET-522]. (See https://issues.apache.org/jira/browse/AMQNET-AMQNET-522)

diff --git a/src/main/csharp/AdvisoryConsumer.cs b/src/main/csharp/AdvisoryConsumer.cs
index 8f8f4f5..90c9046 100644
--- a/src/main/csharp/AdvisoryConsumer.cs
+++ b/src/main/csharp/AdvisoryConsumer.cs
@@ -79,7 +79,7 @@
                     ack.AckType = (byte)AckType.ConsumedAck;
 					ack.ConsumerId = messageDispatch.ConsumerId;
 					ack.Destination = messageDispatch.Destination;
-                    ack.FirstMessageId = messageDispatch.Message.MessageId;
+                    ack.LastMessageId = messageDispatch.Message.MessageId;
                     ack.MessageCount = deliveredCounter;
 
                     this.connection.Oneway(ack);