POST /publicbucket/mymultiloader?uploads=null HTTP/1.1
Host:  [region].telnyxcloudstorage.com
x-amz-acl: public-read
x-amz-storage-class: STANDARD
X-Amz-Date: 20230927T155204Z
Authorization: AWS4-HMAC-SHA256 Credential=YOUR_TELNYX_API_KEY/20230927/test/execute-api/aws4_request, SignedHeaders=host;x-amz-acl;x-amz-date;x-amz-storage-class, Signature=c4b61aa3aa192e1e569c5c6c458138b11f098cbbaaac9f7c88afeb37aa7500ef
Content-Type: text/plain
Content-Length: 22

"<file contents here>"

<?xml version="1.0" encoding="UTF-8"?>
<InitiateMultipartUploadResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
    <Bucket>publicbucket</Bucket>
    <Key>mymultiloader</Key>
    <UploadId>2~vl8z2yj8-4JWQiQJZ1XiS-gUY9sIkcH</UploadId>
</InitiateMultipartUploadResult>