source: src/main/java/com/example/repository/EventRepository.java

package com.example.repository;

import com.example.model.Client;
import com.example.model.Event;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Optional;

@Repository
public interface EventRepository extends JpaRepository<Event,Integer> {
    List<Event> findByClient(Optional<Client> client);

}