curl --request POST \
  --url https://api.hubapi.com/crm/lists/2026-03/idmapping \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '[
  "<string>"
]'

{
  "legacyListIdsToIdsMapping": [
    {
      "legacyListId": "<string>",
      "listId": "<string>"
    }
  ],
  "missingLegacyListIds": [
    "<string>"
  ]
}