👔 Update model

src/model/Student.java

@@ -4,13 +4,13 @@ import java.io.Serializable;
 
 public class Student implements Serializable {
 
-    private final String lastname;
+    private String lastname;
 
     private String firstName;
 
     public Student(String lastname, String firstName) {
-        this.lastname = lastname;
-        this.firstName = firstName;
+        this.lastname = !lastname.isEmpty() ? lastname : "DOE";
+        this.firstName = !firstName.isEmpty() ? firstName : "John";
     }
 
     public String getLastname() {
@@ -24,4 +24,8 @@ public class Student implements Serializable {
     public void setFirstName(String firstName) {
         this.firstName = firstName;
     }
+
+    public void setLastname(String lastname) {
+        this.lastname = lastname;
+    }
 }