How to post using SpringBoot in table with manyToOne relation

I have three classes:

Product:

@Entity
@Table(name ="product")
public class Product {

private long product_id;
private String name;
private double priceWithTax;
private String tax;
private String transportPackage;
private double l_kginTP;
private String category;
private Set<EmployeeProduct> employeeProducts=new HashSet<EmployeeProduct>();

public Product() {
    super();
}

@Id
@GeneratedValue
@Column(name = "product_id")
public long getProduct_id() {
    return product_id;
}

public void setProduct_id(long product_id) {
    this.product_id = product_id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public double getPriceWithTax() {
    return priceWithTax;
}

public void setPriceWithTax(double priceWithTax) {
    this.priceWithTax = priceWithTax;
}

@OneToMany(mappedBy = "product")
public Set<EmployeeProduct> getEmployeeProducts() {
    return employeeProducts;
}

public void setEmployeeProducts(Set<EmployeeProduct> employeeProducts) {
    this.employeeProducts = employeeProducts;
}

public String getTax() {
    return tax;
}

public void setTax(String tax) {
    this.tax = tax;
}

public String getTransportPackage() {
    return transportPackage;
}

public void setTransportPackage(String transportPackage) {
    this.transportPackage = transportPackage;
}

public double getL_kginTP() {
    return l_kginTP;
}

public void setL_kginTP(double l_kginTP) {
    this.l_kginTP = l_kginTP;
}

public String getCategory() {
    return category;
}

public void setCategory(String category) {
    this.category = category;
}

Employee:

@Entity
@Table(name = "employee")
public class Employee {

private long employee_id;
private String name;
private String lastName;
private Set<EmployeeProduct> employeeProducts = new HashSet<EmployeeProduct>();

public Employee() {
    super();
}


public Employee(long id, String name, String lastName) {
    super();
    this.employee_id = id;
    this.name = name;
    this.lastName = lastName;
}

public void addEmployeeProduct(EmployeeProduct eproduct)
{
    this.employeeProducts.add(eproduct);
}

@Id
@GeneratedValue
@Column(name="employee_id")
public long getEmployee_id() {
    return employee_id;
}

public void setEmployee_id(long employee_id) {
    this.employee_id = employee_id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getLastName() {
    return lastName;
}

public void setLastName(String lastName) {
    this.lastName = lastName;
}

@OneToMany(mappedBy="product")
public Set<EmployeeProduct> getEmployeeProducts() {
    return employeeProducts;
}

public void setEmployeeProducts(Set<EmployeeProduct> employeeProducts) {
    this.employeeProducts = employeeProducts;
}   
}

EmployeeProduct:

@Entity
@Table(name="EmployeeProduct")
public class EmployeeProduct {

private long employee_product_id;
private Employee employee;
private Product product;
private Date date;
private double quantityTaken;
private double quantityReturn;
private double quantitySale; 

@Id
@GeneratedValue
@Column(name = "employee_product_id")

public long getEmployee_product_id() {
    return employee_product_id;
}

public void setEmployee_product_id(long employee_product_id) {
    this.employee_product_id = employee_product_id;
}


@JsonIgnore
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "employee_id") 
public Employee getEmployee() {
    return employee;
}

public void setEmployee(Employee employee) {
    this.employee = employee;
}

@JsonIgnore
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "product_id")
public Product getProduct() {
    return product;
}

public void setProduct(Product product) {
    this.product = product;
}


@Column(name = "date")
public Date getDate() {
    return date;
}

public void setDate(Date date) {
    this.date = date;
}

public double getQuantitySale() {
    return quantitySale;
}

public void setQuantitySale(double quantitySale) {
    this.quantitySale = quantitySale;
}

public double getQuantityTaken() {
    return quantityTaken;
}

public void setQuantityTaken(double quantityTaken) {
    this.quantityTaken = quantityTaken;
}

public double getQuantityReturn() {
    return quantityReturn;
}

public void setQuantityReturn(double quantityReturn) {
    this.quantityReturn = quantityReturn;
}
}

I have a controller class where i have this POST:

 @CrossOrigin
    @RequestMapping(value = "/distribution/create", method = RequestMethod.POST)
    public void addEmployee(@RequestBody EmployeeProduct e) {
        EmployeeProduct employeeProduct = new EmployeeProduct();
        employee.setEmployee(e.getEmployee());
        employee.setProduct(e.getProduct());
        employeeService.addEmployee(employeeProduct);
    }

For setEmployee i need to set a long parameters which is foreign key of employee_id but when I send request I need to send object. Also the same situation is with product, when I want to send request I need to send Object for Product but I want to send a foreign key parameter of product.

{
    "employee_id":1,
    "product_id":1,
    "quantity":5
}

For example , quantity will be writed with the POST request but employee_id and product_id wont. Here is the table from the database: