Method map

src/main/java/graphql/collect/ImmutableKit.java:53–62

This is more efficient than `c.stream().map().collect()` because it does not create the intermediate objects needed for the flexible style. Benchmarking has shown this to outperform `stream()`. @param collection the collection to map @param mapper the mapper function @param for two

(Collection<? extends T> collection, Function<? super T, ? extends R> mapper)

     * @return a map immutable list of results
     */
    public static <T, R> ImmutableList<R> map(Collection<? extends T> collection, Function<? super T, ? extends R> mapper) {
        assertNotNull(collection);
        assertNotNull(mapper);
        ImmutableList.Builder<R> builder = ImmutableList.builderWithExpectedSize(collection.size());
        for (T t : collection) {
            R r = mapper.apply(t);
            builder.add(r);
        }
        return builder.build();
    }

    public static <T, R> ImmutableSet<R> mapToSet(Collection<? extends T> collection, Function<? super T, ? extends R> mapper) {
        assertNotNull(collection);