public class TradingAccount {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
  @JoinColumn(name="trading_account_id", referencedColumnName = "trading_account_id", insertable = false, updatable = false)
  private List<UnderlyingPerTradingAccount> underlyingPerTradingAccounts;

  @Version
  private Long version;
}

public class UnderlyingPerTradingAccount {
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;
  @ManyToOne
  @JoinColumn(name="trading_account_id", nullable = false)
  private TradingAccount tradingAccount;
  private Boolean enableBuy;
  private Boolean enableSell;
}