code: public Acl updateBlobAcl(String bucketName, String blobName, long blobGeneration) {
      // [START updateBlobAcl]
      BlobId blobId = BlobId.of(bucketName, blobName, blobGeneration);
      Acl acl = storage.updateAcl(blobId, Acl.of(User.ofAllAuthenticatedUsers(), Role.OWNER));
      // [END updateBlobAcl]
      return acl;
    }
docs: [VARIABLE 42]