@Override
    public boolean remove() {
        if (!this.hooked) {
            return false;
        }

        // clear the internal permissions
        clearInternal();

        // run the callback
        if (this.removalCallback != null) {
            this.removalCallback.attachmentRemoved(this);
        }

        // unhook from the permissible
        this.hooked = false;
        this.permissible.hookedAttachments.remove(this);
        return true;
    }
Hooks this attachment with the parent {@link User} instance.
bukkit/src/main/java/me/lucko/luckperms/bukkit/inject/permissible/LuckPermsPermissionAttachment.java