Upload batches of assets to a sync job that you've created with the POST /asset/{asset_type_name}/{asset_id}/sync/create_job endpoint. This does not add the assets to the catalog directly. Instead, it prepares the sync job to add them once the job is started. Once all the batches have been uploaded to reflect the current state of the source system, start the job using a POST on the /asset/sync/job/{job_id}/ endpoint. The sync job replaces the catalog assets with the assets you upload.