Optional<Integer> a = Optional.of(1);
Optional<Integer> b = Optional.of(1);
Optional<Integer> c = Optional.of(1);

...
if (a.isPresent() && b.isPresent() && c.isPresent()) {
    return a.get() + b.get() + c.get();
}
...

Stream.of(a, b, c)
    .filter(Optional::isPresent)
    .map(Optional::get)
    .mapToInt(Integer::intValue)
    .sum();

Optional<Integer> a = Optional.of(1);
Optional<Integer> b = Optional.of(1);
Optional<Integer> c = Optional.of(1);