GET a collection of V2 and V3 API contact IDs

<div class="Msg Msg--warning"><p class="note-text">Use this endpoint to migrate your locally stored V2 contact ids to the new V3 format. Developers are expected to use this endpoint sparingly. This endpoint is NOT intended for regular or repeated use. Constant Contact will eventually deprecate and remove this endpoint.</p></div>

This GET call retrieves a collection of cross-referenced contact sequence IDs (id used in the V2 API) and UUIDs (contact_id used in the V3 API). This endpoint is intended for developers who have an existing V2 API integration, and are migrating their users to a new V3 API integration. The V2 and V3 APIs use different resource ID formats. Use the sequence_ids query parameter to specify a set of comma delimited V2 contacts ids to cross-referenced with their V3 contact_ids. See Migrating to V3 to learn more.

{
  "xrefs": [
    {
      "sequence_id": "0016633325",
      "contact_id": "ab7ab702-b935-11e9-8a58-fa163e6b01c1"
    }
  ]
}