@Test
public void test_null_less_missing() {

  FunctionExpression less = dsl.less(DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER),
      DSL.ref(INT_TYPE_MISSING_VALUE_FIELD, INTEGER));
  assertEquals(BOOLEAN, less.type());
  assertEquals(LITERAL_MISSING, less.valueOf(valueEnv()));
  less = dsl.less(DSL.ref(INT_TYPE_MISSING_VALUE_FIELD, INTEGER),
      DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER));
  assertEquals(BOOLEAN, less.type());
  assertEquals(LITERAL_MISSING, less.valueOf(valueEnv()));
}