Some jars have snapshot or undefined versions.

jboss-eap-5.1/seam/build/lib/maven-ant-tasks.jar – 2.0.10-SNAPSHOT
jboss-eap-5.1/seam/lib/testng-jdk15.jar – 5.9-200903311355
jboss-eap-5.1/jboss-as/client/jbosssx-as-client.jar – @specification.version@
jboss-eap-5.1/jboss-as/lib/jbosssx-server.jar – @specification.version@
jboss-eap-5.1/jboss-as/client/jnp-client.jar – @specification.version@

For details see http://hudson.qa.jboss.com/hudson/view/EAP5/job/eap51-tattletale/javadoc/invalidversion/index.html