MPRIS seems broken in KDE 5.16.5

Checklist:

• I have checked that there are no issues with similar or the same content (I think similar in #3583 , but that issue in Gnome and not discussed for MPRIS specification.)

  YOU SHOULD CHECK CLOSED ISSUES ASWELL

• I have checked the FAQ (https://github.com/MarshallOfSound/Google-Play-Music-Desktop-Player-UNOFFICIAL-/wiki/FAQ) and the answer I am looking for is not there

• I have double checked and can reproduce the issue

debug_info.zip

OS:

Arch Linux (last updated in about 3:00 UTC)

GPMDP Version:

both:

• 4.6.1 from AUR
• 5332c05

Issue Descriptions:

After updating to KDE5.16.5, the media control applet no longer detects GPMDP. According to KDE changelog, that I think requests more strict MPRIS specification.

Players not compliant to MPRIS specification will no longer work with Media Controller applet. Commit. Phabricator Code review D22596

Steps to Reproduce:

1. Play any music.
2. Media Controller applet has not reaction.
3. Sometimes not working media control keys without MPRIS.