Support Wildcards in directory name in TaildirSource

In our log management project, we wan't to track many log files like this:
/app/dir1/log.*
/app/dir2/log.*
...
/app/dirn/log.*
But TaildirSource can't support wildcards in filegroup directory name. The following config is expected:
a1.sources.r1.filegroups.fg = /app/*/log.*