public boolean isMultipartUpload() {
        return TransferManagerUtils.shouldUseMultipartUpload(origReq, configuration);
    }
Returns true if this UploadCallable is processing a multipart upload.
@return True if this UploadCallable is processing a multipart upload.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/transfer/internal/UploadCallable.java