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

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.
If target is not found in the array, return [-1, -1].
You must write an algorithm with O(log n) runtime complexity.
 
Please complete the following python code precisely:
```python
class Solution:
    def searchRange(self, nums: List[int], target: int) -> List[int]:
```