Missing file in Struts 2 beginners tutorial

The struts2 tutorial at the URL given below lists 9 files that should be added to WEB-INF/lib. commons-lang3-X.X.jar should be added to that list. The downloadable archive given as an example is slightly out of date, but does contain commons-lang-2.5.jar. Without some version of a "commons-lang" library, Apache will fail to start the user's struts2 filter in the following way:

SEVERE: Exception starting filter struts2
java.lang.NoClassDefFoundError: org/apache/commons/lang3/StringUtils

the affected URL is:
https://struts.apache.org/2.2.1/docs/create-struts-2-web-application-with-artifacts-in-web-inf-lib-and-use-ant-to-build-the-application.html