From c71590a6151bcba95c99c44b22530050a33272ca Mon Sep 17 00:00:00 2001
From: Mauro Servienti <mauro.servienti@gmail.com>
Date: Mon, 28 Sep 2020 14:04:26 +0200
Subject: [PATCH] Enable nullable ref types

---
 src/Radical/ChangeTracking/Change Management/Change.cs        | 4 ++--
 .../Properties/PropertyValueChange (Generic).cs               | 2 +-
 src/Radical/Radical.csproj                                    | 2 ++
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/Radical/ChangeTracking/Change Management/Change.cs b/src/Radical/ChangeTracking/Change Management/Change.cs
index d45f95bc..4b0f0328 100644
--- a/src/Radical/ChangeTracking/Change Management/Change.cs	
+++ b/src/Radical/ChangeTracking/Change Management/Change.cs	
@@ -21,7 +21,7 @@ public abstract class Change<T> : IChange<T>
         /// The callback to invoke in order to
         /// commit the cached value.
         /// </summary>
-        protected CommitCallback<T> CommitCallback { get; }
+        protected CommitCallback<T>? CommitCallback { get; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="Change&lt;T&gt;"/> class.
@@ -31,7 +31,7 @@ public abstract class Change<T> : IChange<T>
         /// <param name="rejectCallback">The reject callback.</param>
         /// <param name="commitCallback">The commit callback.</param>
         /// <param name="description">The description.</param>
-        protected Change(object owner, T valueToCache, RejectCallback<T> rejectCallback, CommitCallback<T> commitCallback, string description)
+        protected Change(object owner, T valueToCache, RejectCallback<T> rejectCallback, CommitCallback<T>? commitCallback, string description)
         {
             Ensure.That(owner).Named("owner").IsNotNull();
             Ensure.That(rejectCallback).Named("rejectCallback").IsNotNull();
diff --git a/src/Radical/Model/ChangeTracking/Properties/PropertyValueChange (Generic).cs b/src/Radical/Model/ChangeTracking/Properties/PropertyValueChange (Generic).cs
index 23e3cfb1..4e13341f 100644
--- a/src/Radical/Model/ChangeTracking/Properties/PropertyValueChange (Generic).cs	
+++ b/src/Radical/Model/ChangeTracking/Properties/PropertyValueChange (Generic).cs	
@@ -45,7 +45,7 @@ public PropertyValueChange(object owner, string propertyName, T value, RejectCal
         /// <param name="restoreCallback">The restore callback.</param>
         /// <param name="commitCallback">The commit callback.</param>
         /// <param name="description">The description.</param>
-        public PropertyValueChange(object owner, string propertyName, T value, RejectCallback<T> restoreCallback, CommitCallback<T> commitCallback, string description)
+        public PropertyValueChange(object owner, string propertyName, T value, RejectCallback<T> restoreCallback, CommitCallback<T>? commitCallback, string description)
             : base(owner, value, restoreCallback, commitCallback, description)
         {
             PropertyName = propertyName;
diff --git a/src/Radical/Radical.csproj b/src/Radical/Radical.csproj
index 4145b477..a4fd8f2e 100644
--- a/src/Radical/Radical.csproj
+++ b/src/Radical/Radical.csproj
@@ -2,6 +2,8 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <LangVersion>9</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup>