I have a Class having two fields

```
@Column(name = "transactionDate", nullable = true)
private Date transactionDate;

@Column(name = "nextTransactionDate", nullable = true)
private Date nextTransactionDate

--

```

Both fields can be null. But if transactionDate is not null, then nextTransactionDate must not be null. How can I implement the above relationship between the fields using JPA? Any code snippet, link would be appreciated.

Note: I am using JPA not Hibernate.