code: public Blob copyBlobInChunks(String bucketName, String blobName, String copyBlobName) {
      // [START copyBlobInChunks]
      CopyRequest request =
          CopyRequest.newBuilder()
              .setSource(BlobId.of(bucketName, blobName))
              .setTarget(BlobId.of(bucketName, copyBlobName))
              .build();
      CopyWriter copyWriter = storage.copy(request);
      while (!copyWriter.isDone()) {
        copyWriter.copyChunk();
      }
      Blob blob = copyWriter.getResult();
      // [END copyBlobInChunks]
      return blob;
    }
docs: [VARIABLE "copy_blob_name"]