This should be added alongside the existing in-memory cache in OcspCtSctListExtension.
When storing data to the in-memory cache, also write to the persistent SCT table.
This will require passing some object with callbacks, because OcspCtSctListExtension cannot call session beans (that do the database writes). Re-use the callback object in ECA-8135, if that issue is implemented first. See CTAuditLogCallback for an example callback object.
Update: OcspCtSctListExtension can in fact call session beans, so there is no need for a callback class. Just call the session directly.
Update 2: The OcspCtSctListExtension does in-memory caching on the whole "SCT List extension", so this is not the same as the individual SCTs. We should consider creating a new issue to restructure the existing code, so it caches individual SCTs also. This would require changes in CertificateTransparencyImpl.