title: Open JPA equivalent for Hibernate @ColumnTransformer
body: <p>I am switching ORM framework from Hibernate to OpenJPA.</p>
  
  <p>In Hibernate we could annotate a field with @ColumnTransformer like below.</p>
  
  <pre><code>@Column(name = "EMP_NAME", length = 4000)
  @ColumnTransformer(
          read = "pgp_pub_decrypt(emp_name::bytea,dearmor('"+key1+"'))",
          write = "pgp_pub_encrypt(?, dearmor('"+key2+"'))"
  )
  private String empName;
  </code></pre>
  
  <p>How to do the same in OpenJPA</p>