I'm trying to change spawn.json so that zombies spawn with a random assortment of pieces of iron armor. I've found in the docs how to randomize which kind of armor is applied to an armor slot, and I've found how to randomly decide whether or not to apply a full set of armor, but I've been unable to make either of these accomplish what I'm aiming for; at least not without creating a separate rule for each possible combination of armor.

What I'd like to have is something like this

[
  {
    "mob": ["minecraft:zombie","minecraft:husk"],
	"random": 0.5,
	"armorhelmet": "minecraft:iron_helmet",
	"random": 0.5,
	"armorchest": "minecraft:iron_chestplate",
	"random": 0.5,
	"armorlegs": "minecraft:iron_leggings",
	"random": 0.5,
	"armorboots": "minecraft:iron_boots"
  }
]

This would make it so a zombie could have any combination of pieces of iron armor, with each piece having a 50% chance of being present. The code above actually only lets zombies spawn with a single random piece of armor or no armor.

Is there any way currently to achieve what I'm looking for?
If not, could this feature be added?