Why is Key not required on ObjectTypeDef?

[zjtalia]

Looking at the code for the ObjectTypeDef dictionary:

class ObjectTypeDef(TypedDict):
    Key: NotRequired[str]
    LastModified: NotRequired[datetime]
    ETag: NotRequired[str]
    ChecksumAlgorithm: NotRequired[List[ChecksumAlgorithmType]]
    ChecksumType: NotRequired[ChecksumTypeType]
    Size: NotRequired[int]
    StorageClass: NotRequired[ObjectStorageClassType]
    Owner: NotRequired[OwnerTypeDef]
    RestoreStatus: NotRequired[RestoreStatusTypeDef]

Why is Key marked as NotRequired? When using list_objects_v2 for example, is there ever a scenario where the key for each listed object wouldn't be present? As far as can tell, the key should always be present.