Use groupingBy collector in ListHelper

[Isira-Seneviratne]

What is it?

• Codebase improvement (dev facing)

Description of the changes in your PR

• Use the groupingBy collector in the ListHelper class.

APK testing

The APK can be found by going to the "Checks" tab below the title. On the left pane, click on "CI", scroll down to "artifacts" and click "app" to download the zip file which contains the debug APK of this PR. You can find more info and a video demonstration on this wiki page.

Due diligence

• I read the contribution guidelines.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[Stypox]

I'm sorry, but I think the previous code was just fine. The new code is less understandable, and hides some important implementation details that may cause crashes, e.g. the fact that the map returned by .collect(groupingBy()) might not support .remove() (the documentation says it's a normal Map although from my testing it's a HashMap).