I had the same problem. The solution was to create weblogic-application.xml into the META-INF folder of EAR project. Here is the code.
<?xml version="1.0" encoding="UTF-8"?>
<weblogic-application>
<prefer-application-packages>
<package-name>org.apache.*</package-name>
<package-name>org.springframework.*</package-name>
</prefer-application-packages>
</weblogic-application>
Maybe your problem is that you’re using weblogic.xml into WAR project instead of weblogic-application.xml into EAR project.
Hope it helps.