Yes, you can add a bundle through the API call via SetCatalogItems. The bundle in a catalog is still an item.
According to the API documentation, in the UpdateCatalogItemsRequest, the property Catalog needs a list of CatalogItem. While there is a property named Bundle(which is a CatalogItemBundleInfo ) in the CatalogItem. In the normal circumstance, Bundle property is not required, thus you can assign a CatalogItemBundleInfo instance in order to define this item as a bundle.
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