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

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.
Notice that the solution set must not contain duplicate triplets.
 
Please complete the following python code precisely:
```python
class Solution:
    def threeSum(self, nums: List[int]) -> List[List[int]]:
```