docs: @Nonnull
    @ReturnsMutableCopy
    public static HttpHeaderMap getResponseHeaderMap (@Nonnull final HttpServletResponse aHttpResponse)
    {
      ValueEnforcer.notNull (aHttpResponse, "HttpResponse");
  
      final HttpHeaderMap ret = new HttpHeaderMap ();
      for (final String sName : aHttpResponse.getHeaderNames ())
        for (final String sValue : aHttpResponse.getHeaders (sName))
          ret.addHeader (sName, sValue);
      return ret;
    }