Upload a file to google cloud storage

FrontendController.java

            // Bucket ID is our Project ID
            String bucket = "gs://" + projectIdProvider.getProjectId();

            // Generate a random file name
            filename = UUID.randomUUID().toString() + ".jpg";
            WritableResource resource = (WritableResource)
                    context.getResource(bucket + "/" + filename);

            // Write the file to Cloud Storage using WritableResource
            try (OutputStream os = resource.getOutputStream()) {
                os.write(file.getBytes());
            }