public class Oracle12IdentityGenerator extends IdentityGenerator {
    @Override
    public InsertGeneratedIdentifierDelegate getInsertGeneratedIdentifierDelegate(
            PostInsertIdentityPersister persister, Dialect dialect, boolean isGetGeneratedKeysEnabled)
            throws HibernateException {
        if ( isGetGeneratedKeysEnabled ) {
            return new Oracle12GetGeneratedKeysDelegate(persister, dialect);
        } else {
            return super.getInsertGeneratedIdentifierDelegate(persister, dialect, isGetGeneratedKeysEnabled);
        }
    }

    public static class Oracle12GetGeneratedKeysDelegate extends IdentityGenerator.GetGeneratedKeysDelegate {
        private String[] keyColumns;

        public Oracle12GetGeneratedKeysDelegate(PostInsertIdentityPersister persister, Dialect dialect) {
            super(persister, dialect);
            this.keyColumns = getPersister().getRootTableKeyColumnNames();
            if (keyColumns.length > 1) {
                throw new HibernateException("Identity generator cannot be used with multi-column keys");
            }
        }

        @Override
        protected PreparedStatement prepare(String insertSQL, SessionImplementor session) throws SQLException {
            return session.getTransactionCoordinator()
                    .getJdbcCoordinator()
                    .getStatementPreparer()
                    .prepareStatement(insertSQL, keyColumns);
        }
    }
}