private void copyExtendedData(VCard card, Map<String, Object> contact) {
    safeSet("manager", card.getExtendedProperty("X-Manager"), contact);
    safeSet("spouseName", card.getExtendedProperty("X-Spouse"), contact);
  }
Maps from a VCard to a Microsoft Graph contacts resource as defined by
https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/resources/contact.
extensions/data-transfer/portability-data-transfer-microsoft/src/main/java/org/datatransferproject/transfer/microsoft/transformer/contacts/ToGraphContactTransformer.java