add unique constraint in room database to multiple column : <p>I have one entity in room</p>

<pre><code>@Entity(foreignKeys ={
        @ForeignKey(entity = Label.class, parentColumns = "_id", childColumns = "labelId", onDelete = CASCADE),
        @ForeignKey(entity = Task.class, parentColumns = "_id", childColumns = "taskId", onDelete = CASCADE)
})
public class LabelOfTask extends Data{
    @ColumnInfo(name = "labelId")
    private Integer labelId;
    @ColumnInfo(name = "taskId")
    private Integer taskId;
}
</code></pre>

<p>sql syntax of this entity is as below</p>

<pre><code>CREATE TABLE `LabelOfTask` (
    `_id` INTEGER PRIMARY KEY AUTOINCREMENT,
     `labelId` INTEGER,
     `taskId` INTEGER,
     FOREIGN KEY(`labelId`) REFERENCES `Label`(`_id`) ON UPDATE NO ACTION ON DELETE CASCADE ,
     FOREIGN KEY(`taskId`) REFERENCES `Task`(`_id`) ON UPDATE NO ACTION ON DELETE CASCADE
 );
</code></pre>

<p>but what change or annotation I need to add in entity class if I want to append below constraint to the auto generated sql schema of the table</p>

<pre><code>unique (labelId, taskId)
</code></pre>

<p>Ultimately I want to make combination of labelId and taskId unique in a table(or entity of room) using room library.</p>
