This was discussed with @aozarov in #251. Since `contentType` is a required field we should add it to `Bucket`'s `create(blob, content, options)`: ``` Blob create(String blob, byte[] content, String contentType, BlobTrargetOptions... options) ``` If `contentType` is set to `null` the default content type is used, and we can document this in the javadoc. I propose we use `application/octet-stream` as default.