Add a new subscription record into database. There are two possible situations for add. A. In the first case, the client is only interested in one VCTrust object and the VCTrust object has to exist in database. To make such a subscription, the client need to tell database which VCTrust object he is interested in. The GUID (VCTrust Id) field stands for that specific VCTrust and need to be specified. In this way, the client will only receive notification from that specified object changes. There is no limit on how many subscription an endpoint can add. B. In the second case, the client makes a subscription without a specified VCTrust object, which means the client is interested in every VCTrust object. Whenever the database changes (e.g add a new VCTrust, delete VCTrust, update...), the client gets notified. All the records in the database will not be deleted automatically. The only way to delete a record is to invoke delete API. Warning: This operation is part of a new feature in development. It may be changed at any time and may not have all supported functionality implemented.