RegistryEndpointProvider<URL> writer(URL location, Consumer<Long> writtenByteCountListener) {
    return new Writer(location, writtenByteCountListener);
  }
@Test
  public void testWriter_getContent() throws IOException {
    LongAdder byteCount = new LongAdder();
    BlobHttpContent body = testBlobPusher.writer(mockUrl, byteCount::add).getContent();

    Assert.assertNotNull(body);
    Assert.assertEquals("application/octet-stream", body.getType());

    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    body.writeTo(byteArrayOutputStream);

    Assert.assertEquals(
        TEST_BLOB_CONTENT, new String(byteArrayOutputStream.toByteArray(), StandardCharsets.UTF_8));
    Assert.assertEquals(TEST_BLOB_CONTENT.length(), byteCount.sum());
  }