code: private boolean isTransformableRule(QueryRule nestedRule, String expandAttribute) {
      return nestedRule != null
          && nestedRule.getField() != null
          && nestedRule.getField().equals(expandAttribute)
          && (nestedRule.getOperator() == QueryRule.Operator.IN
              || nestedRule.getOperator() == QueryRule.Operator.EQUALS);
    }
docs: Returns <code>true</code> if a rule is 'IN' or 'EQUALS' on the attribute that should be
  expanded