docs: private static Iterable<HTTPHeader> getHeaders(HTTPResponse resp, String headerName) {
      final String lowercaseHeaderName = headerName.toLowerCase();
      return Iterables.filter(resp.getHeadersUncombined(), new Predicate<HTTPHeader>() {
        @Override public boolean apply(HTTPHeader header) {
          return header.getName().toLowerCase().equals(lowercaseHeaderName);
        }
      });
    }