Hey i found some work arounds for this, you can either call the s3 rest api directly which will work properly, or you can provide the content type when you initiate the multipart upload

eg:

//setting object metadata to have your file content type
ObjectMetadata objectMetadata = new ObjectMetadata();
objectMetadata.setContentType("video/mp4");

// Initiate the multipart upload.
InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(
    bucket,
    key,
    objectMetadata
);

code to uploadPart and also to complete remains the same

@pacey @rafael-adcp

Just a quick update letting you know that the SDK team has reviewed the feature request list for V1 and this looks like a great candidate for a community PR, which we’ll help merge in and support.

I can have a stab at it @debora-ito

I would like help in contributing for this issue. Please message me if you have any questions. I can begin working on it.