private boolean isAllExpression(Expression<?> expr) {
        if (expr instanceof Operation) {
            return ((Operation<?>) expr).getOperator() == SQLOps.ALL;
        } else if (expr instanceof TemplateExpression) {
            return ((TemplateExpression<?>) expr).getTemplate().toString().equals("*");
        } else {
            return false;
        }
    }
{@code NativeSQLSerializer} extends {@link SQLSerializer} to extract referenced entity paths and change
some serialization formats

@author tiwe
querydsl-jpa/src/main/java/com/querydsl/jpa/NativeSQLSerializer.java