A DESCRIPTION OF THE REQUEST :
Provide Optional.or() method similar to Guava with the following implementation:

    public Optional<T> or(Optional<T> other) {
        if (value != null) {
            return this;
        } else {
            return Objects.requireNonNull(other);
        }
    }


JUSTIFICATION :
Having or() method would allow picking the very first non-empty Optional. One can even chain or():

    opt1.or(opt2).or(opt3)

Such method would be really useful and in line with existing orElse().


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Following pseudo-test prints `true` all the way down:

Optional<String> foo = Optional.of("abc");
Optional<String> bar = Optional.of("def");
Optional<String> emp = Optional.empty();

System.out.println(foo.or(bar).get().equals("abc"));
System.out.println(bar.or(foo).get().equals("def"));
System.out.println(foo.or(emp).get().equals("abc"));
System.out.println(emp.or(bar).get().equals("def"));
System.out.println(!emp.or(emp).isPresent());

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