This post is specially for those, having a Java Application(Production) working with SFDC web services via Apache-Axis stubs(WSDL2Java), but because of known advantages from WSC, you want to add some new functionality, like Bulk API as mentioned in SFDC blog.

When we try to use both WSC and Apache Axis WSDL2Java stuff together in the same JVM or Project, we face Java Namespace(Package) clashes. You will certainly get Class-Cast errors like following on first run.

Read More: https://abhinav.fyi/wsc-apache-axis-classcastexception-issue-fixed/