Use the producer Id passed in to the create function.
Fixes [AMQNET-475]. (See https://issues.apache.org/jira/browse/AMQNET-475)

diff --git a/src/main/csharp/Session.cs b/src/main/csharp/Session.cs
index f8289ae..c981bcd 100755
--- a/src/main/csharp/Session.cs
+++ b/src/main/csharp/Session.cs
@@ -455,7 +455,7 @@
 
         internal virtual MessageProducer DoCreateMessageProducer(ProducerId id, ActiveMQDestination destination)
         {
-            return new MessageProducer(this, GetNextProducerId(), destination, this.RequestTimeout);
+            return new MessageProducer(this, id, destination, this.RequestTimeout);
         }
 
         public IMessageConsumer CreateConsumer(IDestination destination)