private boolean hasChildren(final ExpressionOperator operator) {
        if (operator != null && operator.enabled() && operator.getChildren() != null) {
            for (final ExpressionItem child : operator.getChildren()) {
                if (child.enabled()) {
                    if (child instanceof final ExpressionOperator childOperator) {
                        if (hasChildren(childOperator)) {
                            return true;
                        }
                    } else {
                        return true;
                    }
                }
            }
        }

        return false;
    }
Convert our query objects to a LUCENE query.
stroom-index/stroom-index-lucene980/src/main/java/stroom/index/lucene980/SearchExpressionQueryBuilder.java