@Disabled("doesn't return optional statement")
  @Test
  public void debug() {
    assertExpressional(RootCriteria.root.a.isAbsent().a.value().with(a -> a.value.isEmpty()),
            "call op=AND",
            "  call op=IS_ABSENT path=a",
            "  call op=EQUAL path=a.value constant=");
  }
Combination of required and optional fields
criteria/common/test/org/immutables/criteria/nested/NestedTest.java