failureIndexes property
Indexes in to the "failureStrings" lookup table in DestinyVendorDefinition for the given Vendor. Gives some more reliable failure information for why you can't purchase an item. It is preferred to use these over requiredUnlocks and unlockStatuses: the latter are provided mostly in case someone can do something interesting with it that I didn't anticipate.
Implementation
@JsonKey(name:'failureIndexes')
List<int>? failureIndexes;