Determining return type via bitwise operation

Question

I was wandering throught java docs and suddenly found this code:

public static <T, U extends Comparable<? super U>> Comparator<T> comparing(
        Function<? super T, ? extends U> keyExtractor)
{
    Objects.requireNonNull(keyExtractor);
    return (Comparator<T> & Serializable)
        (c1, c2) -> keyExtractor.apply(c1).compareTo(keyExtractor.apply(c2));
}

Can anyone explain what kind of magic is going on after the return statement? Okay, the result of the method is determined by lambda expression in combination with functional interface. But what is it written before that? Is it casting return type via bitwise operation? I don't get it. As far I know bitwise is applicable only with numbers. Where can I read about this case more specifically?

Answer 1

Java 8 adds the ability to cast the lambda into an anonymous intersection. The return type is both a Comparator<T> and Serializable

Referenced from: assylias's answer here

Documentation

NOTE: Java sometimes adds new syntactic meanings to operators in order to maintain backwards compatibility.