ManyToMany save error

При сохранении сущности выпадает ошибка "could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement"

package com.learning.flowershop.Entity;

import javax.persistence.*;
import java.time.LocalDate;
import java.util.Set;

@Entity
@Table(name = "orders")
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private LocalDate orderCreateDate;
    private LocalDate orderCompleteDate;
    @ManyToOne(fetch = FetchType.LAZY)
    private User user;
    @OneToMany
    private Set<Flower> flower;
    private Integer price;

public Order() {
}

public Order(Long id, LocalDate orderCreateDate, LocalDate orderCompleteDate, User user, Set<Flower> flower) {
    this.id = id;
    this.orderCreateDate = orderCreateDate;
    this.orderCompleteDate = orderCompleteDate;
    this.user = user;
    this.flower = flower;
}

public Long getId() {
    return id;
}

public void setId(Long id) {
    this.id = id;
}

public LocalDate getOrderCreateDate() {
    return orderCreateDate;
}

public void setOrderCreateDate(LocalDate orderCreateDate) {
    this.orderCreateDate = orderCreateDate;
}

public LocalDate getOrderCompleteDate() {
    return orderCompleteDate;
}

public void setOrderCompleteDate(LocalDate orderCompleteDate) {
    this.orderCompleteDate = orderCompleteDate;
}

public User getUser() {
    return user;
}

public void setUser(User user) {
    this.user = user;
}

public Set<Flower> getFlower() {
    return flower;
}

public void setFlower(Set<Flower> flower) {
    this.flower = flower;
}

public Integer getPrice() {
    return price;
}

public void setPrice(Integer price) {
    this.price = price;
}
}

С этим body работает

{
"orderCreateDate": "2022-06-23",
"orderCompleteDate": "2022-06-23",
"user": {
   "id": 1 
},
"flower": [{
    "id": 1
},
{
    "id": 2
}],
"price": 500
}

А с этим body - нет

{
"orderCreateDate": "2022-06-23",
"orderCompleteDate": "2022-06-23",
"user": {
   "id": 1 
},
"flower": [{
    "id": 2
},
{
    "id": 2
}],
"price": 500
}

Метод сохранения

@PostMapping("/save")
protected void save(@RequestBody Order order) {
    orderService.saveOrder(order);
}