Before this patch all empty but existing plugin metadata properties was
removed from output as well as `tasks` field that was not respecting
not null constraint at DB level.
As a minor patch payload missing InvalidFileFormat error was added.
Change-Id: I6a21e347fefb7a9a30be562b7fb3e4a8c5c61a36
Partial-Bug: 1616722
Closes-Bug: 1626855