The entity class for comments table should look as follows:

@Entity
@Table(name="comments",catalog="task_mgmt_system")
class Comments {
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   private var id :Int?=null

   @ManyToOne
   @JoinColumn(name = "user_id",nullable = false)
   private var user : User? = null

   @ManyToOne
   @JoinColumn(name = "task_id", nullable = false)
   private var task : Task? = null;

   private var comment:String? = null
 
  // .. Getters and Setters
}

The @ManyToOne annotation is used to declare a many-to-one relationship with a task table. The @JoinColumn annotation is used to define the reference column (primary key).