WFLYEE0097: Module may not be a child of the EAR's library directory. When trying to deploy EAR

Question

I am trying to deploy a web application to WildFly. Right now, I'm simply dropping an ear file in the <JBOSS_HOME>/standalone/deployments directory. When I do, I get the following error message in the marker file:

{"WFLYCTL0080: Failed services" => {"jboss.deployment.unit.\"time4u-assemblies-ear.ear\".STRUCTURE" => "WFLYSRV0153: Failed to process phase STRUCTURE of deployment \"time4u-assemblies-ear.ear\"
    Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: WFLYEE0097: Module may not be a child of the EAR's library directory. Library directory: lib, module file name: lib/time4u-server-api-1.0.4-SNAPSHOT.jar"}}

My initial thought was that the lib/time4u-server-api-1.0.4-SNAPSHOT.jar file was missing. However the file exists in the EAR/lib/ directory.

So what could it mean that the module may not be a child of the EAR's library directory if the file exists? Is this a problem with the application or do I have the wrong approach when trying to deploy it?

I am new to jboss and I did not develop this application myself.