docs: static void setPlotDimensions(final HttpQuery query, final Plot plot) {
      final String wxh = query.getQueryStringParam("wxh");
      if (wxh != null && !wxh.isEmpty()) {
        // TODO - far from perfect, should help a little.
        if (wxh.contains("`") || wxh.contains("%60") || 
            wxh.contains("&#96;")) {
          throw new BadRequestException("WXH contained a back-tick. "
              + "That's a no-no.");
        }
        final int wxhlength = wxh.length();
        if (wxhlength < 7) {  // 100x100 minimum.
          throw new BadRequestException("Parameter wxh too short: " + wxh);
        }
        final int x = wxh.indexOf('x', 3);  // Start at 2 as min size is 100x100
        if (x < 0) {
          throw new BadRequestException("Invalid wxh parameter: " + wxh);
        }
        try {
          final short width = Short.parseShort(wxh.substring(0, x));
          final short height = Short.parseShort(wxh.substring(x + 1, wxhlength));
          try {
            plot.setDimensions(width, height);
          } catch (IllegalArgumentException e) {
            throw new BadRequestException("Invalid wxh parameter: " + wxh + ", "
                                          + e.getMessage());
          }
        } catch (NumberFormatException e) {
          throw new BadRequestException("Can't parse wxh '" + wxh + "': "
                                        + e.getMessage());
        }
      }
    }