docs: @Nonnull
    public final UnifiedResponse setStrictTransportSecurity (final int nMaxAgeSeconds, final boolean bIncludeSubdomains)
    {
      setCustomResponseHeader (CHttpHeader.STRICT_TRANSPORT_SECURITY,
                               new CacheControlBuilder ().setMaxAgeSeconds (nMaxAgeSeconds).getAsHTTPHeaderValue () +
                                                                      (bIncludeSubdomains ? ";" +
                                                                                            CHttpHeader.VALUE_INCLUDE_SUBDOMAINS
                                                                                          : ""));
      return this;
    }