You can add @JoinColumn on the @OneToMany side of relation that make it owner-side like this:

@Entity
public class Employee {
    ...

    @OneToMany(mappedBy="associatedEmployee", cascade=CascadeType.ALL)
    @JoinColumn(name="employee_id")
    private Set<Vehicle> vehicles;

    ...

}

@Entity 
public class Vehicle {
    ...

    @ManyToOne
    private Employee associatedEmployee;

    ...
}

that's set parent and corresponding foreign key automatically.

but I prefer to set parent with setter without change owner side of ManyToOne relation.