Example to illustrate a use case of key-creation in GWT

gistfile1.java

interface HasReferences {
// just an interface,
}

@Entity
public class Person implements HasReferences {
// ...
}

@Entity
public class Company implements HasReferences {
// ...
}

// somewhere in GWT:
List<HasReferences> hasReferences = getHasReferences();

for (HasReferences hr : hasReferences) {
	Key<? extends HasReferences> k = ???;
}