/usr/share/kservices5/akonadi.protocol is in kdepim-runtime 4:15.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | [Protocol]
exec=kf5/kio/akonadi
protocol=akonadi
input=none
output=filesystem
listing=Name,Type
reading=true
writing=false
deleting=true
fileNameUsedForCopying=Name
|