(1) using scala.None in Java, and (2) converting com.google.common.base.Optional to scala.Option

gistfile1.java

import com.google.common.base.Optional;
import scala.None$;
import scala.Option;

public class ScalaLang {

    public static <T> Option<T> none() {
        return (Option<T>) None$.MODULE$;
    }

    public static <T> Option<T> toOption(Optional<T> opt) {
        if(opt.isPresent()) {
            return scala.Option.apply(opt.get());
        }
        else {
            return none();
        }
    }
}