org.bukkit.EntityEffest hasn't been updated for 3 years and is missing many new effects.

There will occure some problems when updating:

• Iron golems and evokation fangs use the same number (4) for their attack. I can not come up with a good name that represents both.
• Same for number 10. It's used for making sheep eat and TNT minecarts explode.
• WOLF_SMOKE and WOLF_HEARTS dont represent thier purpose correctly anymore because also ocelots, parrots, and all horse variations use the same effect. So TAME_SMOKE and TAME_HEARTS would be a better fit.

I also find the documentation to be vague or incomplete sometimes.

/**
 * When a mob dies.
 * <p>
 * <b>This will cause client-glitches!</b>
 */
DEATH(3)

• What is a "mob" exactly
• What does it acctualy do? Play an animation, play a sound, send a message to chat...
• This effect is also used when a snowball or egg brakes