Issue #3502025: Twig default filter makes it hard to decline a default value

Closes #3502025

components/accordion/accordion.twig

@@ -36,7 +36,7 @@
 {% set title_attributes = title_attributes ?: create_attribute() %}
 {% set id = id|default('accordion-' ~ random(1000)) %}
 {% set flush = flush ?? false %}
-{% set items = items|default([]) %}
+{% set items = items ?? [] %}
 {% set open_item_id = open_item_id|default(0) %}
 
 {%