Finish converting all events to jspecify annotations

patches/api/EnderDragon-Events.patch

@@ -142,6 +142,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        this.cancelled = cancel;
 +    }
 +
++    @Override
 +    public HandlerList getHandlers() {
 +        return HANDLER_LIST;
 +    }