Method flatMap

src/main/java/net/minecraftforge/fml/OptionalMod.java:168–175

If a value is present, apply the provided Optional-bearing mapping function to it, return that result, otherwise return an empty Optional. This method is similar to #map(Function), but the provided mapper is one whose result is already an Optional, and if invoked, {@

(Function<? super T, Optional<U>> mapper)

     * a null result
     */
    public<U> Optional<U> flatMap(Function<? super T, Optional<U>> mapper) {
        Objects.requireNonNull(mapper);
        if (!isPresent())
            return Optional.empty();
        else {
            return Objects.requireNonNull(mapper.apply(getValue()));
        }
    }

    /**
     * Return the mod object if present, otherwise return {@code other}.