Migration procedure from v10 to v11(Index calculation)

We are considering migration from v10 (java) to v11 (.net).

Currently, we are verifying the application migration from v10 (java) to v11 (.net), but after migration, the following error occurred when testing the application.

When displaying a list of row selections, the .Net version of the Index calculation is +1 for the Java version.

Therefore, the following state is obtained.

The first line of the list cannot be selected.

If the second line is selected, the data on the first line is displayed.

I've been told that there will be no bugs related to the migration from v10 (java) to v11 (.net).
Please tell me how to solve it.

Just to remove from unanswered, reply made here.