DanielGronau

package dgronau;

import java.util.Objects;
import java.util.Optional;
import java.util.function.*;

public class Optional2<A, B> {

    private final Optional<A> first;
    private final Optional<B> second;

DanielGronau

import java.math.BigInteger

abstract class Constraint

abstract class Property {
    abstract val required: Boolean
    abstract val constraints: List<Constraint>
}

abstract class DocumentConstraint : Constraint()