inStreamVideoAsset.setName(assetName);
inStreamVideoAsset.setContent(Media.getMediaDataFromFile(pathToFile));
// Create an upload request to make this asset a companion ad file for an
// existing In-Stream video creative.
InStreamAssetUploadRequest inStreamAssetUploadRequest = new InStreamAssetUploadRequest();
inStreamAssetUploadRequest.setCompanion(true);
inStreamAssetUploadRequest.setInStreamAsset(inStreamVideoAsset);
inStreamAssetUploadRequest.setCreativeId(creativeId);
// Replace the existing asset with a newly uploaded asset.
InStreamVideoCreative inStreamVideoCreative =
creativeService.replaceInStreamAsset(assetToReplace, inStreamAssetUploadRequest);