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

An integer array original is transformed into a doubled array changed by appending twice the value of every element in original, and then randomly shuffling the resulting array.
Given an array changed, return original if changed is a doubled array. If changed is not a doubled array, return an empty array. The elements in original may be returned in any order.
 
Please complete the following python code precisely:
```python
class Solution:
    def findOriginalArray(self, changed: List[int]) -> List[int]:
```