Add missing "WithWill..." methods.

.github/workflows/ReleaseNotes.md

@@ -1 +1,2 @@
 * [Client] Fixed MQTTv5 protocol violation in PUBLISH packets (#1423).
+* [Client] Added missing "WithWill..." methods in _MqttClientOptionsBuilder_.

Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs

@@ -380,6 +380,17 @@ namespace MQTTnet.Client
             return this;
         }
         
+        public MqttClientOptionsBuilder WithWillPayload(string willPayload)
+        {
+            if (string.IsNullOrEmpty(willPayload))
+            {
+                return WithWillPayload((byte[])null);
+            }
+            
+            _options.WillPayload = Encoding.UTF8.GetBytes(willPayload);
+            return this;
+        }
+
         public MqttClientOptionsBuilder WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel willQualityOfServiceLevel)
         {
             _options.WillQualityOfServiceLevel = willQualityOfServiceLevel;
@@ -391,5 +402,46 @@ namespace MQTTnet.Client
             _options.WillTopic = willTopic;
             return this;
         }
+
+        public MqttClientOptionsBuilder WithWillRetain(bool willRetain = true)
+        {
+            _options.WillRetain = willRetain;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillContentType(string willContentType)
+        {
+            _options.WillContentType = willContentType;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillCorrelationData(byte[] willCorrelationData)
+        {
+            _options.WillCorrelationData = willCorrelationData;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillResponseTopic(string willResponseTopic)
+        {
+            _options.WillResponseTopic = willResponseTopic;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillPayloadFormatIndicator(MqttPayloadFormatIndicator willPayloadFormatIndicator)
+        {
+            _options.WillPayloadFormatIndicator = willPayloadFormatIndicator;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillUserProperty(string name, string value)
+        {
+            if (_options.WillUserProperties == null)
+            {
+                _options.WillUserProperties = new List<MqttUserProperty>();
+            }
+            
+            _options.WillUserProperties.Add(new MqttUserProperty(name, value));
+            return this;
+        }
     }
 }