How to summon a cluster/group of mobs Minecraft(JAVA)

Today i will show you how to summon a bunch of mobs all at once. This can be used for maps etc.
COMMANDS:
/summon minecraft:area_effect_cloud ~ ~10 ~ {Duration:3,Tags:[spawn],Passengers:[{id:zombie,Tags:[spread]},{id:zombie,Tags:[spread]},{id:zombie,Tags:[spread]}]}
/execute as @e[tag=spread] run data merge entity @s {ActiveEffects:[{Id:18,Duration:3,ShowParticles:0b},{Id:14,Amplifier:200,Duration:10,ShowParticles:0b},{Id:2,Duration:10,Amplifier:200,ShowParticles:0b}]}
/execute at @e[tag=spawn] run spreadplayers ~ ~ 1 2 false @e[tag=spread,distance=..10]
/tag @e[tag=spread] remove spread