>> params = {"line_items"=>[{"quantity"=>"1"}, {"quantity"=>"2"}]}
=> {"line_items"=>[{"quantity"=>"1"}, {"quantity"=>"2"}]}

>> query = CGI::unescape(params.to_query)
=> "line_items[][quantity]=1&line_items[][quantity]=2"

>> parsed_params = ActionController::AbstractRequest.parse_query_parameters(query)
=> {"line_items"=>[{"quantity"=>"1"}, {"quantity"=>"2"}]}

>> params == parsed_params
=> true