Please solve the programming task below using a self-contained code snippet in a markdown code block.

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums.
 
Please complete the following python code precisely:
```python
class Solution:
    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
```