While investigating mod-inventory-storage API test failures, it was noticed that
- two sample data records use "null" value that breaks JSON schema validation. Suggest to remove those "null" values.
- one reference data uses "null" as instance status code. Suggest to change "null" to "none".
- null instance status code. See https://github.com/folio-org/mod-inventory-storage/blob/v15.5.1/reference-data/instance-statuses/notyetassigned.json#L3