code: public static String getWidgetBanner(String guildId, BannerType type)
      {
          Checks.notNull(guildId, "GuildId");
          Checks.notNull(type, "BannerType");
          return String.format(WIDGET_PNG, guildId, type.name().toLowerCase());
      }
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. Additionally, this method can be used independently of
  being on the guild in question.
  
  @param  guildId
  the guild ID
  @param  type
  The type (visual style) of the banner
  
  @return A String containing the URL of the banner image