items property
The items that represent your reward for completing the quest. Be warned, these could be "dummy" items: items that are only used to render a good-looking in-game tooltip, but aren't the actual items themselves. For instance, when experience is given there's often a dummy item representing "experience", with quantity being the amount of experience you got. We don't have a programmatic association between those and whatever Progression is actually getting that experience... yet.
Implementation
@JsonKey(name:'items')
List<DestinyMilestoneQuestRewardItem>? items;