gistfile1.txt

public class PersonSpecifications {

    public static Specification<Person> hasFirstName(String firstName) {
        return (root, query, cb) -> cb.equal(root.get("firstName"), firstName);
    }

    public static Specification<Person> hasLastName(String lastName) {
        return (root, query, cb) -> cb.equal(root.get("lastName"), lastName);
    }

    public static Specification<Person> hasAge(Integer age) {
        return (root, query, cb) -> cb.equal(root.get("age"), age);
    }

}

public interface PersonRepository extends JpaRepository<Person, Long> {

    List<Person> findAll(Specification<Person> spec);

}

Specification<Person> spec = PersonSpecifications.hasFirstName("John")
        .and(PersonSpecifications.hasLastName("Doe"))
        .and(PersonSpecifications.hasAge(30));

List<Person> results = personRepository.findAll(spec);