Jpa get parent by field child

How to get parent entity by child's field? I use Specification

I have repository

ParentRepository extends JpaRepository<Parent, Long>, JpaSpecificationExecutor<Parent>{
}

And two clases:

 class Parent{
    @Id
    long id;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = ID_CHILD)
    Child child;
    }



  class Child{
    @ID
    long id;

   @OneToOne(mappedBy = "child", cascade = CascadeType.ALL)
   Parent parent;

    Date date;
    }

I need to get parent by field of child. Need Parent who has child with date between two dates.

I tried to write class ParentSpecification but don't understand how to get it done.

public class ParentSpecification {
    private ParenSpecification() {
    }
    public static Specification<Parent> byChildName(Date one,  Date two){
        return (root, query, criteriaBuilder) -> {
           ??????????            
return criteriaBuilder....
        };
    }
}

Following code may help you. Here find the parent by the child date. You may change according to your need.

public class ParentSpecification {

    public static Specification<Parent> byChildDate(Date one, Date two){
        return (root, query, criteriaBuilder) ->
            criteriaBuilder.between(root.get("child").get("date"), one, two);
    }
}