Fix special syntax

Author: inputfalken

src/DynamoDBGenerator.SourceGenerator/Constants.cs

@@ -81,6 +81,7 @@ public static class Marshaller
         public static class AttributeValueUtilityFactory
         {
             private const string ClassName = "MarshallHelper";
+            public const string ToAttributeValue = $"{ClassName}.ToAttributeValue";
             public const string Null = $"{ClassName}.Null";
             public const string ToList = $"{ClassName}.ToList";
             public const string ToArray = $"{ClassName}.ToArray";

src/DynamoDBGenerator.SourceGenerator/Generations/Marshalling/Marshaller.cs

@@ -216,7 +216,7 @@ internal static string InvokeMarshallerMethod(ITypeSymbol typeSymbol, string par
 
         if (typeSymbol.TypeIdentifier() is UnknownType)
             return typeSymbol.IsNullable()
-                ? $"{invocation} switch {{ {{ }} x => new {Constants.AWSSDK_DynamoDBv2.AttributeValue} {{ M = x }}, null => null }}"
+                ? $"{AttributeValueUtilityFactory.ToAttributeValue}({invocation})"
                 : $"new {Constants.AWSSDK_DynamoDBv2.AttributeValue} {{ M = {invocation} }}";
 
         return invocation;

src/DynamoDBGenerator/Internal/MarshallHelper.cs

@@ -17,6 +17,9 @@ public static class MarshallHelper
 #pragma warning disable CS1591
     public static AttributeValue Null { get; } = new() { NULL = true };
 
+    public static AttributeValue? ToAttributeValue(Dictionary<string, AttributeValue>? dict) => dict is null 
+        ? null 
+        : new AttributeValue { M = dict };
 
     public static AttributeValue FromDictionary<T, TArgument>(
         IEnumerable<KeyValuePair<string, T>> dictionary,