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