@Test
public void test_nested_to_string() {

  Aggregator sumAggregator = dsl.sum(dsl.multiply(DSL.ref("integer_value", INTEGER),
      DSL.literal(ExprValueUtils.integerValue(10))));
  assertEquals(String.format("sum(*(%s, %d))", DSL.ref("integer_value", INTEGER), 10),
      sumAggregator.toString());
}