Person2.java

@Entity
public class Person {
  @Value
  private String firstName;
  @Value
  private String middleName;
  @Value
  private String lastName;

  Person() {}

  public Person(
      String firstName,
      Optional<String> middleName,
      String lastName) {
    Objects.requireNonNull(firstName);
    Objects.requireNonNull(lastName);
    this.firstName = firstName;
    this.middleName = middleName.orNull();
    this.lastName = lastName;
  }

  public String getFirstName() {
    return firstName;
  }

  public Optional<String> getMiddleName() {
    return Optional.fromNullable(middleName);
  }

  public String getLastName() {
    return lastName;
  }
}