After searching web and looking into Wildfly community class loading document I found that WildFly gets Confused if we bundle EJB view interfaces in EAR/lib separately along with EJB jar files. SO basically our application had Interfaces for EJB beans in each EJB jar file and also all interfaces were put in separate jar file within ear/lib directory so that they can be accessed by Servlets or JSF components to call EJB bean methods. But this resulted in ClassCast Exception in Wildfly10.1. Such a setup was working perfectly in Jboss-4.2.2, Jboss-6.0.0.Final but not with WildFly10.
Hope it helps other who face similar problem in migration.