Classpath entry ... jar will not be exported or published. Runtime ClassNotFoundExceptions may result.

To avoid the following warning in Eclipse:
"Classpath entry ... jar will not be exported or published. Runtime ClassNotFoundExceptions may result."

Add the following attribute to the mentioned classpath entry in the project ".classpath" file.

Example
<classpathentry kind="var" path="M2_REPO/javax/ejb/ejb-api/3.0/ejb-api-3.0.jar">
<attributes>
<attribute name="org.eclipse.jst.component.nondependency" value=""/>
</attributes>
</classpathentry>