Nullable fields that hold JsFunctions have wrong generated types

[niloc132]

Java input:

@JsFunction
public interface TransportFactory {
  Transport create(Options options);
}

@JsNullable
public TransportFactory transportFactory

Resulting field:

transportFactory?:(options:Options)=>Transport|null;

The type of that field is incorrect - as written it says that the function might return null, instead of saying that the field is allowed to be null. Correct options could be

Put the null first:

transportFactory?:null|(options:Options)=>Transport;

Add parens around functions if they are going to be unioned

transportFactory?:((options:Options)=>Transport)|null;