Deploy the jboss-as-login.war example. It depends on the "ExampleDS" datasource. Access the web application. Disable and enable the datasource. Try the web app again:

13:11:26,599 INFO  [org.jboss.as.controller] (HttpManagementService-threads - 4) JBAS014774: Service status report
JBAS014776:    Newly corrected services:
      service jboss.naming.context.java.jboss.datasources.ExampleDS (no longer required)

This error prevails as long as the deployment is not disabled and re-eanbled again