Use information of pojo attribute when generating typescript type

Question

I use jsweet to generate a typescript file from a Pojo.

This is the simplified java class :

public class Menu {
  public long id;

  public String label;

  @my.custom.annotation.Nullable
  public List<my.package.Menu> children;
}

It generates

/* Generated from Java with JSweet 3.1.0 - http://www.jsweet.org */
export class Menu {
    public id: number;

    public label: string;

    public children: Array<Menu>;

    constructor() {
        if (this.id === undefined) { this.id = null; }
        if (this.label === undefined) { this.label = null; }
        if (this.children === undefined) { this.children = null; }
    }
}
ContextMenu["__class"] = "my.package.Menu";

I would like to generate a different type depending on the presence or absence of @Nullable.

I would like this to be generated :

/* Generated from Java with JSweet 3.1.0 - http://www.jsweet.org */
export class Menu {
    public id: number;

    public label: string;

    public children: Array<Menu> | undefined;
    // or maybe this would make more sens :
    // public children?: Array<Menu>;

    constructor() {
        if (this.id === undefined) { this.id = null; }
        if (this.label === undefined) { this.label = null; }
        if (this.children === undefined) { this.children = null; }
    }
}
ContextMenu["__class"] = "my.package.Menu";

So far I have to tried to create a PrinterAdapter and override addTypeMapping(Function<TypeMirror, String>). I also tried to override addTypeMapping(BiFunction<ExtendedElement, String, Object>).

But in both cases I can only access the attribute type and not the field itself.

Here is the code that doesn't work

    addTypeMapping(new BiFunction<ExtendedElement, String, Object>() {

      @Override
      public Object apply(ExtendedElement extendedElement, String s) {

        final TypeMirror typeMirror = extendedElement.getType();
        final String mappedType = getMappedType(typeMirror);
        
        // here typeMirror is a my.pacakge.Menu

        if (typeMirror.getKind() == TypeKind.DECLARED) {
          DeclaredType declaredType = (DeclaredType) typeMirror;
          Element element = declaredType.asElement();

          final my.custom.annotation.Nullable nullable =
              element.getAnnotation(my.custom.annotation.Nullable.class);
          if (nullable != null) {
            return mappedType + " | null";
          }
        }

        return getMappedType(typeMirror);
      }
    });

I also looked inside the JSweetContext available with getContext() but could not find a way to access information about the attribute whose type is currently mapped.