It's been possible to create an SDC with a prop that has a type: array shape.
During the 1.3.x releases we've been working towards making the Content Authoring experience for these SDCs actually work.
In 1.3.4 we've reached the point where they are fully supported, including type: array props that are required. However, such required props MUST specify:
minItems: 1
(Because this aligns with Drupal's existing Entity/Field API semantics.)
🙈 MEA CULPA: we have been gating the development of this functionality behind a feature flag, but we've unfortunately been focused on getting it to work from beginning to end for code components. Some of you may have noticed the component instance form kinda started working for SDCs as well. It shouldn't have. It should've been gated as well. So some of you may experience a small amount of disruption: you'd need to A) add minItems: 1 to your SDC(s), B) clear all caches, C) edit existing instances of such SDCs to automatically update to the latest version of the component.
