docs: @Nonnull
    public final UnifiedResponse enableCaching (@Nonnegative final int nSeconds)
    {
      ValueEnforcer.isGT0 (nSeconds, "Seconds");
  
      // Remove any eventually set headers
      // Note: don't remove Last-Modified and ETag!
      removeExpires ();
      removeCacheControl ();
      m_aResponseHeaderMap.removeHeaders (CHttpHeader.PRAGMA);
  
      if (m_eHttpVersion.is10 ())
      {
        m_aResponseHeaderMap.setDateHeader (CHttpHeader.EXPIRES,
                                            PDTFactory.getCurrentLocalDateTime ().plusSeconds (nSeconds));
      }
      else
      {
        final CacheControlBuilder aCacheControlBuilder = new CacheControlBuilder ().setPublic (true)
                                                                                   .setMaxAgeSeconds (nSeconds);
        setCacheControl (aCacheControlBuilder);
      }
      return this;
    }