@Override public String url() {
    StringBuffer url = delegate.getRequestURL();
    if (delegate.getQueryString() != null && !delegate.getQueryString().isEmpty()) {
      url.append('?').append(delegate.getQueryString());
    }
    return url.toString();
  }
@Test void url_derivedFromUrlAndQueryString() {
    when(request.getRequestURL()).thenReturn(new StringBuffer("http://foo:8080/bar"));
    when(request.getQueryString()).thenReturn("hello=world");

    assertThat(wrapper.url())
      .isEqualTo("http://foo:8080/bar?hello=world");
  }