code: public static String getWidgetBanner(Guild guild, BannerType type)
      {
          Checks.notNull(guild, "Guild");
          return getWidgetBanner(guild.getId(), type);
      }
docs: Gets the banner image for the specified guild of the specified type.
  <br>This banner will only be available if the guild in question has the
  Widget enabled.
  
  @param  guild
  The guild
  @param  type
  The type (visual style) of the banner
  
  @return A String containing the URL of the banner image