JBAS013227: Could not start app client content as no main class was found - when calling appclient.sh on application in data/content in JBoss EAP 6

Issue

• When calling appclient.sh on an application client in the JBoss content repository, it throws JBAS013227: Could not start app client content as no main class was found

$JBOSS_HOME/bin/appclient.sh --host=remote://localhost:4447 ./standalone/data/content/9c/d0080f4879f261bef5aa404cff64d21d8b520a/content#application-client.jar

The error is:

14:31:21,762 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-2) MSC000001: Failed to start service jboss.deployment.unit.content.INSTALL: org.jboss.msc.service.StartException in service jboss.deployment.unit.content.INSTALL: JBAS018733: Failed to process phase INSTALL of deployment "content"
    at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:166) [jboss-as-server-7.4.3.Final-redhat-2.jar:7.4.3.Final-redhat-2]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1980) [jboss-msc-1.1.5.Final-redhat-1.jar:1.1.5.Final-redhat-1]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1913) [jboss-msc-1.1.5.Final-redhat-1.jar:1.1.5.Final-redhat-1]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
    at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]
Caused by: java.lang.RuntimeException: JBAS013227: Could not start app client content as no main class was found
    at org.jboss.as.appclient.deployment.ApplicationClientStartProcessor.deploy(ApplicationClientStartProcessor.java:105) [jboss-as-appclient-7.4.3.Final-redhat-2.jar:7.4.3.Final-redhat-2]
    at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:159) [jboss-as-server-7.4.3.Final-redhat-2.jar:7.4.3.Final-redhat-2]
    ... 5 more