@SuppressWarnings("unchecked")
  private void addEmail(Email email, Map<String, Object> map) {
    List<Map<String, String>> collection =
        (List<Map<String, String>>) map.computeIfAbsent("emailAddresses", k -> new ArrayList<>());
    Map<String, String> emailMap = new LinkedHashMap<>();
    emailMap.put("address", email.getValue());
    collection.add(emailMap);
  }
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