Description of problem:
In Xfce's application list the icon provided by the package is not used. Hence a generic icon is used.

Furthermore, there is a strange string, "#ARCH#", in the desktop file of the policytool.

Version-Release number of selected component (if applicable):
$ rpm -qf /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.181.b15-0.fc29.x86_64/jre/bin/policytool
java-1.8.0-openjdk-1.8.0.181.b15-0.fc29.x86_64

How reproducible:
easy, 100%

Steps to Reproduce:
1. install/start Xfce as desktop environment
2. go to: Applications -- Settings

Actual results:
Item "OpenJDK 8 Policy Tool #ARCH#" does not use provided icon file, but the generic black/white icon.

Expected results:
Use provided icon file.
Maybe replace "#ARCH#" with actual arch of computer, i.e. x86_64 or x86 or ...

Additional info:
Problem can be found in former Fedora versions too, f.i. Fedora 28.

Fixing the icon here will also fix it for this item:
Applications -- Development -- OpenJDK 8 Monitoring & Management Console 1.8.0.181-7.b13.fc28.x86_64
provided by package java-1.8.0-openjdk-devel



The problem with the icon file: the desktop file requires a file that is not provided by the package.
The desktop file requires:
$ grep Icon `rpm -ql java-1.8.0-openjdk | grep desktop`
Icon=java-8-openjdk


Which is not available:
$ sudo dnf whatprovides "*/java-8-openjdk*"
...
Error: No Matches found


The package provides icons, but with a different name:
$ rpm -ql java-1.8.0-openjdk
...
/usr/share/applications/java-1.8.0-openjdk-1.8.0.181.b15-0.fc29.x86_64-policytool.desktop
/usr/share/icons/hicolor/16x16/apps/java-1.8.0.png
/usr/share/icons/hicolor/24x24/apps/java-1.8.0.png
/usr/share/icons/hicolor/32x32/apps/java-1.8.0.png
/usr/share/icons/hicolor/48x48/apps/java-1.8.0.png


Two solutions are possible:
Either update desktop file to use "java-1.8.0" in the Icon line.

Or create a copy or symlink to these files, f.i. with:
$ sudo ln -s /usr/share/icons/hicolor/48x48/apps/java-1.8.0.png /usr/share/icons/hicolor/48x48/apps/java-8-openjdk.png
and update icon cache file:
$ sudo gtk-update-icon-cache /usr/share/icons/hicolor
gtk-update-icon-cache: Cache file created successfully.


In Xfce you might need to log out and in again in order to see the update.