static void assertExpectedIpv4(Endpoint endpoint) {
    assertThat(endpoint.ipv4())
      .isEqualTo("43.0.192.2");
    assertThat(endpoint.ipv4Bytes())
      .containsExactly(43, 0, 192, 2);
    assertThat(endpoint.ipv6())
      .isNull();
    assertThat(endpoint.ipv6Bytes())
      .isNull();
  }
Catches common error when zero is passed instead of null for a port
zipkin/src/test/java/zipkin2/EndpointTest.java