@Mojo(name="attach-descriptor",
      defaultPhase=PACKAGE,
      threadSafe=true)
public class SiteDescriptorAttachMojo
extends AbstractSiteDescriptorMojo

Adds the site descriptor (site.xml) to the list of files to be installed/deployed.
For Maven-2.x this is enabled by default only when the project has pom packaging since it will be used by modules inheriting, but this can be enabled for other projects packaging if needed.
This default execution has been removed from the built-in lifecycle of Maven 3.x for pom-projects. Users that actually use those projects to provide a common site descriptor for sub modules will need to explicitly define this goal execution to restore the intended behavior.