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

Given two binary search trees root1 and root2, return a list containing all the integers from both trees sorted in ascending order.
 
Please complete the following python code precisely:
```python
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def getAllElements(self, root1: TreeNode, root2: TreeNode) -> List[int]:
        
```