Android - Room autoGenerate not found

I am trying to make an id as primary key and set it to autoGenerate. Somehow, when I compile my code I get this error:

"autoGenerate not found"

Here is my code:

@Entity
public class Preference {

    @PrimaryKey(autoGenerate = true)
    private int id;

    public void setId(int id) {

    this.id = id;

}