Within the context of a JEE EAR, I understand the purpose of the classpath entry in a WAR's Manifest.mf file as well as in an EJB's jar file. However, I do not understand the purpose in that of the EAR file.
Is the EAR's classpath somehow supposed to be inherited by the enclosed WARs? For instance, if my EAR has some entries in the classpath, do i need to reiterate them in that of my war? If so, then why bother with setting it up in the EAR file?
The EJB jar also has its own Classpath in the Manifest, so what/how is the EAR's classpath entry used?
As far as the JavaEE specifications are concerned, a Class-Path entry in an EAR file's manifest file serves no purpose at all and will be ignored.
There is some chance that a vendor specific extension uses it, but I have not seen it on JBoss/WildFly, WebLogic or WebSphere.
You can read all about it in §8.2 of the Java EE 7 Specification.