Anyone knows if it is possible to use prefix and delimiter options at the same time like the following raw REST URL

https://www.googleapis.com/storage/v1/b/clientbuilds/o?delimiter=%2F&prefix=dir1%2Fdir2%2F&key={YOUR_API_KEY}

(above is from https://developers.google.com/apis-explorer/#p/storage/v1/storage.objects.list?)
Results from this is:

{
 "kind": "storage#objects",
 "prefixes": [
  "dir1/dir2/6893940/",
  "dir1/dir2/6893942/"
 ]
}

Setting the prefix I know how to do with Storage.BlobListOption.prefix("dir1/dir2/")but I looked in the code and can't really understand how to set the delimiter