You can store arbitrary metadata with HIPS in some endpoints that will be returned whenever you view the same endpoint (example: Order).
Two reference fields is used to store arbitrary data (example: internal order reference).
The reference fields are meta_data_1 and meta_data_2
{
"meta_data_1": "any_custom_reference",
"meta_data_2": "{\"my_reference\":1,\"name\":\"test\"}"
}
Do not store any data as meta data that you do not want the consumer to have access to. In some json returns to customers browser the meta data is visible. If you want to store secret information as meta data is should be encrypted before you send the data to Hips.
JSON as metadata?
Yes, but make sure it is escaped before you send it.