docs: @Nonnull
    @ReturnsMutableCopy
    public static HttpHeaderMap getRequestHeaderMap (@Nonnull final HttpServletRequest aHttpRequest)
    {
      ValueEnforcer.notNull (aHttpRequest, "HttpRequest");
  
      final HttpHeaderMap ret = new HttpHeaderMap ();
      final Enumeration <String> aHeaders = aHttpRequest.getHeaderNames ();
      while (aHeaders.hasMoreElements ())
      {
        final String sName = aHeaders.nextElement ();
        final Enumeration <String> eHeaderValues = aHttpRequest.getHeaders (sName);
        while (eHeaderValues.hasMoreElements ())
        {
          final String sValue = eHeaderValues.nextElement ();
          ret.addHeader (sName, sValue);
        }
      }
      return ret;
    }