[Plugin] Http/s REST, blueprintable JSON and Parse REST API manager at once (VaRest)

I have a problem, my json object does have the good format, but on my $_POST (yes in php) i don’t have params which is arrays.
Is any problem with passing arrays ?

[EDIT] I found a solution : encode as json string my object containing array then pass it to a string field of the request object. And on the server side, do a json_decode and assign the return value to $_POST