Cannot modify image assets used in MSI installer
I'm successfully packaging MSI files using the Gradle plugin, however I cannot yet specify the images used in the MSI installer.
These are screenshots from the MSI while installing it:

This is what I'm trying to achieve, swap out the images on the left in the first screen and the banner at the top of the second screen:

As explained in the WIX documentation it is possible to set those images using these options in main.wxs, for example like this:
<?define JpResources = $(env.GRADLE_PROJECT_DIR)\src\jpackage\assets?>
<WixVariable Id="WixUIBannerBmp" Value="$(var.JpResources)\banner.bmp" />
<WixVariable Id="WixUIDialogBmp" Value="$(var.JpResources)\dialog.bmp" />
in order for this to work two things are necessary:
- we need to be able to add additional resources into the directory passed to
jpackagewith flag--resource-dir(#1972) - we need to have some way to define an environment variable that is accessible from thw WX toolchain process
I have a solution for 1.) ready here at: #2331 and a solution for 2.) at #2336.
Please check the following ticket on YouTrack for follow-ups to this issue. GitHub issues will be closed in the coming weeks.