this.blobstore = checkNotNull(blobstore, "blobstore");
this.containerName = checkNotNull(containerName, "container");
checkArgument(containerName.indexOf('/') == -1,
"please specify directory path using the option: inDirectory, not encoded in the container name");
this.options = checkNotNull(options, "options") instanceof ImmutableListContainerOptions ? options
: new ImmutableListContainerOptions(options);
String dir = options.getDir();
if (dir == null) {
prefixer = identity();
pathStripper = prefixer;
} else {