If you war has a MANIFEST.MF with empty classpath you get an error even though empty Class-Path: is present (and afaik valid).

This is btw. how Eclipse defaults to create a war with no jar dependencies thus it would fail for a lot of folks

11:53:53,682 INFO [org.jboss.as.server.deployment] (MSC service thread 1-2) Starting deployment of "jbossas7-deploy-example.war"
11:53:53,706 WARN [org.jboss.vfs] (MSC service thread 1-1) VFS was unable to set the URLStreamHandlerFactory. This will have unpredictable results
11:53:53,731 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-2) MSC00001:Failed to start service jboss.deployment.unit."jbossas7-deploy-example.war".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."jbossas7-deploy-example.war".PARSE: Failed to process phase PARSE of deployment "jbossas7-deploy-example.war"
at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:109)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1367)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [:1.6.0_22]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [:1.6.0_22]
at java.lang.Thread.run(Thread.java:680) [:1.6.0_22]
Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: Class Path entry in "/content/jbossas7-deploy-example.war" not found.
at org.jboss.as.server.deployment.module.ManifestClassPathProcessor.deploy(ManifestClassPathProcessor.java:123)
at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:103)
... 4 more

I'm attaching a simple war showing this.