public Expression rewrite(final Expression expression) {
    return new ExpressionTreeRewriter<>(new OperatorPlugin()::process)
        .rewrite(expression, null);
  }
@Test
  public void shouldReplaceComparisonOfWindowEndAndString() {
    // Given:
    final Expression predicate = getPredicate(
        "SELECT * FROM orders where WINDOWEND > '2017-01-01T00:00:00.000';");

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

    // Then:
    assertThat(rewritten.toString(), is(String.format("(WINDOWEND > %d)", A_TIMESTAMP)));
  }