A base configuration file named struts-default.xml is included in the struts2.jar file. This file is automatically included into struts.xml file to provide the standard configuration settings without having to copy them.

The contents of struts-default.xml are here:

This file defines all of the default bundled results and interceptors and many interceptor stacks which you can use either as-is or as a basis for your own application-specific interceptor stacks. Notice the name of the package is "struts-default".