Zamiana `equals` na `instanceof`

if (ex != null && ex instanceof PersistenceException) {
 PersistenceException e = (PersistenceException) ex;
 if (e.getCause() != null) {
 Throwable providerException = e.getCause();
 if ("org.hibernate.exception.ConstraintViolationException".equals(providerException.getClass().getName())) {

if (providerException instanceof ConstraintViolationException) {
 // ...
}