How to make an "Object " in JSON which will take two "List

I have developed a code in which i have to test it by sending an object to a class named say "hello " which has 2 List in it as :- Testing is done through "Postman" with Json as the input format.

class hello 
{
Long<List> l1=new ArrayList<Long>;
Long<List> l2=new ArrayList<Long>;
......
}

In this the object which i have created is of the form { "queryIds":" <[104,105]>", "userIds" : "[-1,-21]" }

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but it gives me the response that :

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"Message": "Invalid data supplied for request, incorrect data type used.", Leading to a failure , Please tell me how to declare the object . Thanx in advance