how to maintain lastupdated date of fhir resource while migrating Data

**Question**

we are moving from SQL to Cosmos, so we want to migrate data from SQL to cosmos but we don't want to change the lastupdated date of FHIR Reasourse, how can we achieve this.

No file, test, or entry point is named. Start by reviewing the SQL-to-Cosmos migration path and how FHIR resource lastUpdated is handled; done would require a confirmed, documented migration approach that preserves the existing date.

Written by the indexing model from the issue text.