Update v10_00.md

Author: mythz

MyApp/_pages/releases/v10_00.md

@@ -572,6 +572,24 @@ export class CreateBooking implements IReturn<IdResponse>, ICreateDb<Booking>
 }
 ```
 
+### Override Nullable Annotations
+
+Languages with nullable annotations like TypeScript will allow you to control optional properties for each property with `IsPropertyOptional`, e.g:
+
+```csharp
+TypeScriptGenerator.IsPropertyOptional = (ts, type, prop) =>
+{
+    // Custom Impl
+    if (ShouldBeOptional(type, prop))
+        return true;
+    if (ShouldBeRequired(type, prop))
+        return false;
+        
+    // Default Impl
+    return TypeScriptGenerator.DefaultIsPropertyOptional(ts, type, prop);
+};
+```
+
 ## SVG Creator
 
 To reduce the artifacts in our starting project templates we're replacing SVGs for pre-configured users to use inline data URIs which is now generated using the new `SvgCreator` class which lets you create random SVG images from the first letter of a users name and a random background color: