How does the Explosive M+ affix work in World of Warcraft in relation to 'AoE spells'?

Looking at the Mythic Plus affixes this week, there are

TYRANNICAL BOLSTERING EXPLOSIVE INFESTED

The explosive affix is stated to be:

Creatures have a chance to summon an Explosive Orb at a nearby location that will explode, inflicting damage 50% of the player’s maximum health as damage.

Note: An explosive orb will spawn with a 6 second cast. If the cast goes off the entire party will take 50% of their max hp in damage. They are AOE immune so you can't cleave them down! They can also spawn on boss fights.

The note mentions that they are AoE immune and cannot be cleaved down. Which spells count as AoE? Would a spell such as Chain Lightning be considered AoE?

You can't bounce Chain Lightning from other targets onto Explosive enemies. Essentially, attacks will only hit Explosive enemies when the attack is aimed directly at the Explosive as the main selected target. Chain Lightning won't cleave to them, Cleave won't cleave to them, Living Bomb won't spread to them,... The intent for the affix is for the players to react when they spawn and immediately kill them within 1 or 2 attacks. They don't have a lot of HP, but they do spawn in amounts relative to the size of the group of mobs you are in combat with, so large pulls can easily overwhelm you. Be careful with pulls like the Ticks in Underrot, for example.