License question

Hello,

From what I've read, if I have 10 licensed (Defender for Office 365) users, each with their own mailbox and an additional shared mailbox connected, I only need to license those 10 users (the shared mailbox doesn't need to be licensed additionally). However, I don't see such a provision in the licensing agreements themselves. If I understand this correctly, can someone point me to the relevant clause in the agreement?

Does a shared mailbox that no one uses require a Defender license (if the organization uses Defender for Office 365 licenses)?

thx.