docs: public void multiPartUpload(File file, String bucketName) {
          AmazonS3 client = new AmazonS3Client(creds);
          bucketName = ensureValidBucketName(bucketName);
  
          List<Bucket> buckets = client.listBuckets();
          for (Bucket b : buckets)
              if (b.getName().equals(bucketName)) {
                  doMultiPart(client, bucketName, file);
                  return;
              }
  
          //bucket didn't exist: create it
          client.createBucket(bucketName);
          doMultiPart(client, bucketName, file);
      }