JSpecify: Missing compile error when reused method returns @Nullable to @NonNull constructor #4081

@Mapper
@NullMarked
public interface ErroneousIssue4081Mapper {
    Target map(Source source);

    default Target.@Nullable Payload mapPayload(String payload) {
        if ( payload.isBlank() ) {
            return null;
        }
        return new Target.Payload( payload );
    }
}

public class Source {
    private final String payload;

    public @NonNull String getPayload() { return this.payload; }
}

public class Target {
    private final Payload payload;
    public Target(@NonNull Payload payload) { this.payload = payload; }

    public class Payload {
        private final String value;
        public Payload(@NonNull String value) { this.value = value; }
    }
}

@Generated
public class ErroneousIssue4081MapperImpl implements ErroneousIssue4081Mapper {

    @Override
    public Target map(Source source) {

        Target.Payload payload = null;

        payload = mapValue( source.getPayload() );

        Target target = new Target( payload );

        return target;
    }
}