Desktop launchers ignore unthemed icons containing dot in its name

Like https://bugzilla.xfce.org/show_bug.cgi?id=15294, icons located in /usr/share/pixmaps/ containing dot (.) in its name are ignored.

Steps to Reproduce

1. Place an icon under /usr/share/pixmaps (i.e. /usr/share/pixmaps/test.icon.png).
2. Create a .desktop entry on the desktop and make it reference the new icon by name (i.e. Icon=test.icon)

Other info

The system is Ubuntu Focal. Output of xfdesktop --version is:

This is xfdesktop version 4.14.2, running on Xfce 4.14.
Built with GTK+ 3.24.13, linked with GTK+ 3.24.20.
Build options:
    Desktop Menu:        enabled
    Desktop Icons:       enabled
    Desktop File Icons:  enabled

I found this issue when trying to install VScode from its official deb package and create an icon on desktop for it. The icon file for VScode is located at /usr/share/pixmaps/com.visualstudio.code.png.