User

User.java

```java import java.util.*;

public class User { private String name; private List familyMembers = new ArrayList<>();

// Validation
public User(String name) {
    if (name == null || name.trim().isEmpty()) {
        throw new IllegalArgumentException("Name required");
    }
    this.name = name.trim();
}

// Validation
public void addFamilyMember(FamilyMember fm) {
    if (fm != null)
        familyMembers.add(fm);
}

public List<FamilyMember> getFamilyMembers() {
    return Collections.unmodifiableList(familyMembers);
}

public String getName() {
    return name;
   }
}
```