@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
    @LazyCollection(LazyCollectionOption.FALSE)
    @JoinColumn(name = "ORGANIZATION_ID")
    private Collection<Department> departments = new ArrayList<>();

public Organization saveOrganization(Organization organization) {
        Collection<Department> toSave = new ArrayList<>();
            for (Department department : organization.getDepartments()) {
                department.setOrganization(organization);
                toSave.add(department);   
            }
        departmentRepository.save(toSave));
        organization.setDepartments(toSave);
        return organizationRepository.save(organization);      
}

public class Department{
    ....
    @ManyToOne
    @JoinColumn(name = "ORGANIZATION_ID", referencedColumnName = "ID")
    private Organization organization;