Merge pull request #30 from Havret/exception_is_throw_on_transport_thread_during_shutdown

AMQNET-611: Apache.NMS.IllegalStateException is throw on transport thread
diff --git a/src/NMS.AMQP/NmsMessageConsumer.cs b/src/NMS.AMQP/NmsMessageConsumer.cs
index 34afd0c..a8c65d5 100644
--- a/src/NMS.AMQP/NmsMessageConsumer.cs
+++ b/src/NMS.AMQP/NmsMessageConsumer.cs
@@ -408,7 +408,7 @@
             {
                 envelope.Message.NmsAcknowledgeCallback = new NmsAcknowledgeCallback(Session);
             }
-            else if (Session.AcknowledgementMode == AcknowledgementMode.IndividualAcknowledge)
+            else if (Session.IsIndividualAcknowledge())
             {
                 envelope.Message.NmsAcknowledgeCallback = new NmsAcknowledgeCallback(Session, envelope);
             }
diff --git a/src/NMS.AMQP/NmsSession.cs b/src/NMS.AMQP/NmsSession.cs
index c9f008d..1b1c0f6 100644
--- a/src/NMS.AMQP/NmsSession.cs
+++ b/src/NMS.AMQP/NmsSession.cs
@@ -592,5 +592,7 @@
                 consumer.OnConnectionInterrupted();
             }
         }
+
+        internal bool IsIndividualAcknowledge() => acknowledgementMode == AcknowledgementMode.IndividualAcknowledge;
     }
 }
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