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

You are given a 0-indexed array nums consisting of positive integers. You can choose two indices i and j, such that i != j, and the sum of digits of the number nums[i] is equal to that of nums[j].
Return the maximum value of nums[i] + nums[j] that you can obtain over all possible indices i and j that satisfy the conditions.
 
Please complete the following python code precisely:
```python
class Solution:
    def maximumSum(self, nums: List[int]) -> int:
```