fix bug when mapWith arguments does not save nullability for referenc…

NextGenMapper/Mapping/Designers/ConfiguredMapDesigner.cs

@@ -141,7 +141,7 @@ private static void DesignConfiguredMaps(
                 continue;
             }
 
-            var destinationPropertyType = destinationProperty.Type.ToNotNullableString();
+            var destinationPropertyType = destinationProperty.Type.ToDisplayString();
             if (arguments.Contains(destinationProperty.Name))
             {
                 var propertyMap = CreateUserProvidedProeprtyMap(destinationProperty.Name, destinationPropertyType);

NextGenMapperTests/Snapshots/ConfiguredMap/PropertyType/MapResult/NullableReferenceTypesInArgumentWithMapMethodCall_ShouldMap.verified.txt

@@ -0,0 +1,6 @@
+{
+  PropertyThatNeedMap: {
+    Property: good
+  },
+  Property: good
+}

NextGenMapperTests/Snapshots/ConfiguredMap/PropertyType/NullableReferenceTypesInArgumentWithMapMethodCall_ShouldMap.00Mapper_ConfiguredMaps_MockMethods.g.verified.cs

@@ -0,0 +1,19 @@
+//HintName: Mapper_ConfiguredMaps_MockMethods.g.cs
+#nullable enable
+using NextGenMapper.Extensions;
+
+namespace NextGenMapper
+{
+    internal static partial class Mapper
+    {
+        internal static Test.Destination MapWith<To>
+        (
+            this Test.Source source,
+            Test.B? PropertyThatNeedMap = default!,
+            string Property = default!
+        )
+        {
+            throw new System.NotImplementedException("This method is a mock and is not intended to be called");
+        }
+    }
+}

NextGenMapperTests/Snapshots/ConfiguredMap/PropertyType/NullableReferenceTypesInArgumentWithMapMethodCall_ShouldMap.01Mapper_ConfiguredMaps.g.verified.cs

@@ -0,0 +1,20 @@
+//HintName: Mapper_ConfiguredMaps.g.cs
+#nullable enable
+using NextGenMapper.Extensions;
+
+namespace NextGenMapper
+{
+    internal static partial class Mapper
+    {
+        internal static Test.Destination MapWith<To>
+        (
+            this Test.Source source,
+            Test.B? PropertyThatNeedMap
+        )
+        => new Test.Destination
+        {
+            PropertyThatNeedMap = PropertyThatNeedMap,
+            Property = source.Property
+        };
+    }
+}

NextGenMapperTests/Tests/AutomaticCustomizedMapping/PropertyType.cs

@@ -549,4 +549,43 @@ public class B
 
         await VerifyAndRun(source);
     }
+
+    [TestMethod]
+    public async Task NullableReferenceTypesInArgumentWithMapMethodCall_ShouldMap()
+    {
+        var source =
+@"#nullable enable
+using NextGenMapper;
+
+    namespace Test;
+
+    public class Program
+    {
+        public object RunTest() => new Source().MapWith<Destination>(PropertyThatNeedMap: new B { Property = ""good"" });
+    }
+
+    public class Source
+    {
+        public A? PropertyThatNeedMap { get; set; } = null;
+        public string Property { get; set; } = ""good"";
+    }
+
+    public class Destination
+    {
+        public B? PropertyThatNeedMap { get; set; }
+        public string Property { get; set; } = ""bad"";
+    }
+
+    public class A
+    {
+        public string Property { get; set; } = string.Empty;
+    }
+
+    public class B
+    {
+        public string Property { get; set; } = ""bad"";
+    }";
+
+        await VerifyAndRun(source);
+    }
 }