public static Matcher<HttpRequest> pathStartsWith(String pathPrefix) {
    if (pathPrefix == null) throw new NullPointerException("pathPrefix == null");
    if (pathPrefix.isEmpty()) throw new NullPointerException("pathPrefix is empty");
    return new PathStartsWith(pathPrefix);
  }
@Test void pathStartsWith_unmatched_null() {
    assertThat(pathStartsWith("/foo").matches(httpRequest)).isFalse();
  }