public static BlobId of(String bucket, String name, Long generation) {
    return new BlobId(checkNotNull(bucket), checkNotNull(name), generation);
  }
public static BlobId of ( String bucket , String name , Long generation ) { return new BlobId ( checkNotNull ( bucket ) , checkNotNull ( name ) , generation ) ; }
Creates a {@code BlobId} object.

@param bucket name of the containing bucket
@param name blob's name
@param generation blob's data generation, used for versioning. If {@code null} the identifier
refers to the latest blob's generation