@Udf
  public String extractHost(
      @UdfParameter(description = "a valid URL") final String input) {
    return UrlParser.extract(input, URI::getHost);
  }
@Test
  public void shouldExtractHostIfPresent() {
    assertThat(extractUdf.extractHost("https://docs.confluent.io:8080/current/ksql/docs/syntax-reference.html#scalar-functions"), equalTo("docs.confluent.io"));
  }