@Test public void parseClientIpAndPort_prefersXForwardedFor() {

  when(adapter.requestHeader(request, "X-Forwarded-For")).thenReturn("1.2.3.4");
  adapter.parseClientIpAndPort(request, span);
  verify(span).remoteIpAndPort("1.2.3.4", 0);
  verifyNoMoreInteractions(span);
}