Invalid artifact issue of Eclipselink Nexus Proxy Repository

I use Nexus as my internal maven repository. I set up a proxy repository "Eclipselink Maven Mirror" for Eclipselink. Eclipselink uses this URL http://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/rt/eclipselink/maven.repo which actually redirects you to a mirror site. Just put this link into "Remote Storage Location" and create a proxy repository. I made Eclipselink repository as the last one in "Ordered Group Repository" in "Public Repository" Configuration tab. My maven settings.xml defines a mirror to use the public repository group like this

    <mirrors>
        <mirror>
            <id>nexus-public</id>
            <mirrorOf>*</mirrorOf>
            <url>http://nexus:8080/nexus/content/groups/public</url>
        </mirror>
    </mirrors>

Unfortunately it doesn't work well. When maven gets some of artifacts, especially my own artifacts, Nexus returns invalid pom or jar files in this "Eclipselink Maven Mirror", which are actually HTML pages. And the artifacts will be saved into maven local repository, and make my maven builds fail again and again. I don't know how Nexus search the public repositories to locate an artifact. But looks like Nexus tries "EclipseLink Maven Mirror", then access the Eclipselink Repo using the URL listed above. Unfortunately this URL will return a HTML page once the artifact is not found. But Nexus didn't check if it is invalid because I didn't configure it. Here is my solution:

• Setup two mirrors: one for eclipselink and one for the others except eclipselink.

        
            nexus-public
            *,!eclipselink-repo
            http://nexus:8080/nexus/content/groups/public
        
        
            nexus-eclipselink
            eclipselink-repo
            http://nexus:8080/nexus/content/repositories/eclipselink-maven-mirror
        

• Set "File Content Validation" to true For "Eclipselink Maven Mirror"