ClassCastException: xx.Sample cannot be cast to xx.Sample when using Remote API

Issue

When using Remote API to invoke the process, following exception is raised:

09:33:22,824 WARN  [org.drools.persistence.SingleSessionCommandService] (http-/0.0.0.0:443-11) Could not commit session: java.lang.ClassCastException: com.test.space.Sample cannot be cast to com.test.space.Sample

What is the reason for it? The FQCN of both classes is the same.