There is an unique constraint on a column of a table. So I want to put an annotation for the entity attribute associated to that column :

package com.fnptechnologies.logic.resto;

import java.io.Serializable;

import jakarta.persistence.Basic;
import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
import jakarta.validation.constraints.NotNull;
import lombok.Data;

@Entity
@Data
@Table(name = "t_pos_calendrier_serveur")
public class TPosCalendrierServeur implements Serializable {
    
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;

    @Column(name = "mmc_user_id")
    @NotNull
    // here the annotation for unique constraint 
    private int mmcUserId;
    
}

So what is the annotation for the unique constraint ?