Is one of the two fields required DLE?

Question

DLE

The essence of the question is how to implement the following:
There are two fields, and one of them is mandatory.
1 field) File, if the file was uploaded then field 2 is optional.
2 field) link, if the link was inserted then field 1 is optional)
If both fields are not filled, and they click on the add button, then they are asked to fill in one of these two fields. Please advise, thank you.