diff --git a/Doc/SerializationAttributes.aml b/Doc/SerializationAttributes.aml
index 8b313f91..b05adc0b 100644
--- a/Doc/SerializationAttributes.aml
+++ b/Doc/SerializationAttributes.aml
@@ -124,6 +124,10 @@
         <para>The <codeEntityReference>T:Newtonsoft.Json.JsonExtensionDataAttribute</codeEntityReference> instructs the
         <codeEntityReference>T:Newtonsoft.Json.JsonSerializer</codeEntityReference> to deserialize properties with no matching field or property
         on the type into the specified collection. During serialization the values in this collection are written back to the instance's JSON object.</para>
+
+<alert class="note">
+  <para>All extension data values will be written during serialization, even if a property the same name has already been written.</para>
+</alert>        
         <para>This example shows the JsonExtensionDataAttribute being applied to a field, unmatched JSON properties being added to the field's collection during deserialization.</para>
         <code lang="cs" source="..\Src\Newtonsoft.Json.Tests\Documentation\Samples\Serializer\DeserializeExtensionData.cs" region="Types" title="Types" />
         <code lang="cs" source="..\Src\Newtonsoft.Json.Tests\Documentation\Samples\Serializer\DeserializeExtensionData.cs" region="Usage" title="Usage" />
diff --git a/Src/Newtonsoft.Json/Linq/JObject.cs b/Src/Newtonsoft.Json/Linq/JObject.cs
index 25e71fad..55e13d75 100644
--- a/Src/Newtonsoft.Json/Linq/JObject.cs
+++ b/Src/Newtonsoft.Json/Linq/JObject.cs
@@ -706,10 +706,7 @@ namespace Newtonsoft.Json.Linq
         /// <param name="propertyName">Name of the property.</param>
         protected virtual void OnPropertyChanged(string propertyName)
         {
-            if (PropertyChanged != null)
-            {
-                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
-            }
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
         }
 
 #if !(PORTABLE40 || PORTABLE || NET20)
@@ -719,10 +716,7 @@ namespace Newtonsoft.Json.Linq
         /// <param name="propertyName">Name of the property.</param>
         protected virtual void OnPropertyChanging(string propertyName)
         {
-            if (PropertyChanging != null)
-            {
-                PropertyChanging(this, new PropertyChangingEventArgs(propertyName));
-            }
+            PropertyChanging?.Invoke(this, new PropertyChangingEventArgs(propertyName));
         }
 #endif