@Entity
@javax.persistence.Table(name = "tb_myTable")
@org.hibernate.annotations.Table(appliesTo = "tb_myTable", fetch=FetchMode.JOIN, indexes={ @Index(name="my_idx", columnNames={"field","another"}) } )

public class MyClass {
   private double field;
   private double another;
   ....
   
   @Column
   public double getField() {
      return field;
   }

   public void setField(double field) {
      this.field = field;
   }

   @Column
   public double getAnother() {
      return another;
   }

   public void setAnother(double another) {
      this.another = another;
   }
       ...
}