From 1b18ac9fe3d41acff4499775ff20775730364685 Mon Sep 17 00:00:00 2001
From: Ramon Smits <ramon.smits@gmail.com>
Date: Mon, 29 May 2023 12:38:33 +0200
Subject: [PATCH] Resolve ConvertPayloadToString resulting in
 ArgumentNullException (#1745)

Resolve breaking change where previously ConvertPayloadToString returned null if the payload was null
---
 Source/MQTTnet/MqttApplicationMessageExtensions.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Source/MQTTnet/MqttApplicationMessageExtensions.cs b/Source/MQTTnet/MqttApplicationMessageExtensions.cs
index 1f3b9059..fd59a667 100644
--- a/Source/MQTTnet/MqttApplicationMessageExtensions.cs
+++ b/Source/MQTTnet/MqttApplicationMessageExtensions.cs
@@ -4,6 +4,7 @@
 
 using System;
 using System.Text;
+using MQTTnet.Internal;
 
 namespace MQTTnet
 {
@@ -16,6 +17,11 @@ namespace MQTTnet
                 throw new ArgumentNullException(nameof(applicationMessage));
             }
 
+            if(applicationMessage.PayloadSegment == EmptyBuffer.ArraySegment)
+            {
+                return null;
+            }
+
             var payloadSegment = applicationMessage.PayloadSegment;
             return Encoding.UTF8.GetString(payloadSegment.Array, payloadSegment.Offset, payloadSegment.Count);
         }