Fix default valeu for reference types and non-reference types (#34)

* .

* ok

* sw

* .

* .

tests/ProxyInterfaceSourceGeneratorTests/Source/Person.cs

@@ -28,6 +28,26 @@ namespace ProxyInterfaceSourceGeneratorTests.Source
         {
             return $"Hello {name} !";
         }
+        
+        public string HelloWorld2(string? name = "x")
+        {
+            return $"Hello {name} !";
+        }
+
+        public string HelloWorld3(char? ch = 'c')
+        {
+            return $"Hello {ch} !";
+        }
+
+        public string HelloWorld4(char ch)
+        {
+            return $"Hello {ch} !";
+        }
+
+        public string HelloWorld5(char? ch)
+        {
+            return $"Hello {ch} !";
+        }
 
         public void WithParams(params string[] values)
         {
@@ -70,7 +90,7 @@ namespace ProxyInterfaceSourceGeneratorTests.Source
             return Task.FromResult((string?)"");
         }
 
-        public void CreateInvokeHttpClient(int i = 5, string? appId = null, CancellationToken token = default)
+        public void CreateInvokeHttpClient(int i = 5, string? appId = null, IReadOnlyDictionary<string, string> metadata = null, CancellationToken token = default)
         {
         }
     }