public static Builder builder() {
    return new Builder();
  }
@Test
  public void testJsonSerializeDeserialize() {
    // default key created by S3Options.SSECustomerKeyFactory
    SSECustomerKey emptyKey = SSECustomerKey.builder().build();
    assertThat(jsonSerializeDeserialize(emptyKey)).isEqualToComparingFieldByField(emptyKey);

    SSECustomerKey key = SSECustomerKey.builder().key("key").algorithm("algo").md5("md5").build();
    assertThat(jsonSerializeDeserialize(key)).isEqualToComparingFieldByField(key);
  }