private abstract Optional<String> methodThatReturnsOptionalString();
private void useOptionalString() {
Optional<String> myOptionalString = methodThatReturnsOptionalString();
if (myOptionalString.isPresent()) {
String myUnboxedString = myOptionalString.get();
System.out.format("Optional string had value: %s\n", myUnboxedString);
} else {