Build error: Package `libxfconf-0' not found in specified Vala API directories or GObject-Introspection GIR directories

Hello!

While building latest master the build fails with:

make[2]: Entering directory '/home/rootmonk/Downloads/todo/hacking/xfce4-notes-plugin/lib'
  VALAC    libnotes_la_vala.stamp
error: Package `libxfconf-0' not found in specified Vala API directories or GObject-Introspection GIR directories
Compilation failed: 1 error(s), 0 warning(s)

Thanks!