Determine batching from metadata in ConsumerChannel based on ShouldSerializeNumMessagesInBatch (#63)

diff --git a/src/DotPulsar/Internal/ConsumerChannel.cs b/src/DotPulsar/Internal/ConsumerChannel.cs
index a84e574..7ea2255 100644
--- a/src/DotPulsar/Internal/ConsumerChannel.cs
+++ b/src/DotPulsar/Internal/ConsumerChannel.cs
@@ -86,9 +86,9 @@
                     var metadata = messagePackage.ExtractMetadata(metadataSize);
                     var messageId = messagePackage.MessageId;
 
-                    return metadata.NumMessagesInBatch == 1
-                        ? new Message(new MessageId(messageId), redeliveryCount, metadata, null, data)
-                        : _batchHandler.Add(messageId, redeliveryCount, metadata, data);
+                    return metadata.ShouldSerializeNumMessagesInBatch()
+                        ? _batchHandler.Add(messageId, redeliveryCount, metadata, data)
+                        : new Message(new MessageId(messageId), redeliveryCount, metadata, null, data);
                 }
             }
         }