public Expression rewrite(final Expression expression) {
    return new ExpressionTreeRewriter<>(new OperatorPlugin()::process)
        .rewrite(expression, null);
  }
@Test
  public void shouldNotReplaceUnsupportedColumns() {
    // Given:
    final Expression predicate = getPredicate(
        "SELECT * FROM orders where ROWTIME > '2017-01-01' AND ORDERTIME = '2017-01-01';");

    // When:
    final Expression rewritten = rewriter.rewrite(predicate);

    // Then:
    assertThat(rewritten.toString(),
        is(String.format("((ORDERS.ROWTIME > %d) AND (ORDERS.ORDERTIME = '2017-01-01'))",
            A_TIMESTAMP)));
  }