The bug
When I discovered that selectors stopped breaking, i hopped into a minecraft world to tinker a bit with fireworks and commands. When I tried to summon a fireworks_rocket with custom NBT tags to make it have different colors, it always appeared black.
Steps to reproduce
Go to a minecraft world in 1.12-pre5. (Make sure the world has cheats enabled.)
Use this command:
/summon fireworks_rocket ~5 ~ ~ {LifeTime:0,FireworksItem:{id:fireworks,Count:1,tag:{Fireworks:{Explosions:[{Type:1,Flicker:0,Trail:1,Colors:[0,16777215,14408448],FadeColors:[8026746]}]}}}}
The firework is supposed to have custom colors, but it doesn't.
Close Minecraft, and open version 1.11.2
Go to a world in this version
Use the command as described in point 2.
The firework does have custom colors.
NBT phrasing changed, to declare an int array (not list of ints)(fireworks uses an int array for colors) do this:
instead of