Oracle: JSON_ARRAY_T

declare
 
   json_text      clob;
   json_obj       json_object_t;
   array_of_array json_array_t;
   array          json_array_t;
   elem           json_element_t;
  
begin
 
   json_text      := 
   '{
     "data": [
        [1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]
      ]
    }';
  
   json_obj       := json_object_t.parse(json_text);
   array_of_array := json_obj.get_array('data');
   array          := treat(array_of_array.get(1) as json_array_t);
   elem           := array.get(0);
  
   dbms_output.put_line(elem.to_number()); -- 4
  
end;
/