Code cleanup (#1461)

* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error

role-object/src/main/java/com/iluwatar/roleobject/CustomerCore.java

@@ -36,7 +36,7 @@ import java.util.Optional;
  */
 public class CustomerCore extends Customer {
 
-  private Map<Role, CustomerRole> roles;
+  private final Map<Role, CustomerRole> roles;
 
   public CustomerCore() {
     roles = new HashMap<>();

role-object/src/main/java/com/iluwatar/roleobject/Role.java

@@ -34,7 +34,7 @@ public enum Role {
 
   Borrower(BorrowerRole.class), Investor(InvestorRole.class);
 
-  private Class<? extends CustomerRole> typeCst;
+  private final Class<? extends CustomerRole> typeCst;
 
   Role(Class<? extends CustomerRole> typeCst) {
     this.typeCst = typeCst;