Monad Builder in Java

MonadBuilder.java

public static final class Builder {
  private final String firstName;
  private final String lastName;
  private final String middleName;

  public static Builder builder() {
      return new Builder("", "", "");
  }

  private Builder(String firstName, String middleName, String lastName) {
      this.firstName = firstName;
      this.middleName = middleName;
      this.lastName = lastName;
  }

  public Builder withFirstName(final String val) {
      return new Builder(val, middleName, lastName);
  }

  public Builder withMiddleName(final String val) {
      return new Builder(firstName, val, lastName);
  }

  public Builder withLastName(final String val) {
      return new Builder(firstName, middleName, val);
  }

  public Person build() {
      return new Person(this);
  }
}