How FireworkAPI work?

Plugins Plugin Development
1

Hi, anyone knows how Firework API works? I tried to build effect with the builder but i don’t know how it put it in the firework

Cheers!

2 
//FireworkEffect effect; ItemStack item;
item.offer(Keys.FIREWORK_EFFECTS, ImmutableList.of(effect));
item.offer(Keys.FIREWORK_DELAY, 2);
3

Thanks, it works!