diff --git a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/KeyValueElement.Serialization.cs b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/KeyValueElement.Serialization.cs
index c45b0443706e0..b12c7b5aec857 100644
--- a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/KeyValueElement.Serialization.cs
+++ b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/KeyValueElement.Serialization.cs
@@ -15,7 +15,7 @@ internal partial class KeyValueElement
     {
         internal static KeyValueElement DeserializeKeyValueElement(JsonElement element)
         {
-            Optional<KeyValueType> type = default;
+            Optional<KeyValueType?> type = default;
             string text = default;
             Optional<IReadOnlyList<float>> boundingBox = default;
             Optional<IReadOnlyList<string>> elements = default;
@@ -25,7 +25,7 @@ internal static KeyValueElement DeserializeKeyValueElement(JsonElement element)
                 {
                     if (property.Value.ValueKind == JsonValueKind.Null)
                     {
-                        property.ThrowNonNullablePropertyIsNull();
+                        type = null;
                         continue;
                     }
                     type = new KeyValueType(property.Value.GetString());
diff --git a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/ReadResult.Serialization.cs b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/ReadResult.Serialization.cs
index 954952640630f..1a8d2e6d525f2 100644
--- a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/ReadResult.Serialization.cs
+++ b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/Generated/Models/ReadResult.Serialization.cs
@@ -80,7 +80,7 @@ internal static ReadResult DeserializeReadResult(JsonElement element)
                 {
                     if (property.Value.ValueKind == JsonValueKind.Null)
                     {
-                        property.ThrowNonNullablePropertyIsNull();
+                        selectionMarks = null;
                         continue;
                     }
                     List<SelectionMark> array = new List<SelectionMark>();
diff --git a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/autorest.md b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/autorest.md
index c0c7d8b31541c..8433f7710bc89 100644
--- a/sdk/formrecognizer/Azure.AI.FormRecognizer/src/autorest.md
+++ b/sdk/formrecognizer/Azure.AI.FormRecognizer/src/autorest.md
@@ -32,6 +32,22 @@ directive:
     $.properties.documentResults["x-nullable"] = true;
 ```
 
+``` yaml
+directive:
+  from: swagger-document
+  where: $.definitions.ReadResult
+  transform: >
+    $.properties.selectionMarks["x-nullable"] = true;
+```
+
+``` yaml
+directive:
+  from: swagger-document
+  where: $.definitions.KeyValueType
+  transform: >
+    $["x-nullable"] = true;
+```
+
 ``` yaml
 directive:
   from: swagger-document