plugin dlls from mozilla/plugins directory are not removed during jre uninstallation

Tested Build : mustang jre build 72 - 78
Tested OS : windows

1. Install mustang any jre build from 72 to 78
2. go to mozilla.org/mozilla/plugins directory
3. Make sure that np*.dlls available (npjava11.dll, npjava12.dll, npjava13.dll, npjava14.dll,npjava32.dll,npjpoi160.dll,npoji610.dll)under plugins directory
4. uninstall mustang jre build
the dlls are still available in the mozilla.org/mozilla/plugins directory

Expected behavior : These dlls should be removed