When jpackageHome is not configured, the default toolchain java home is used to determine the binary even when javaHome is configured in the extension.

The current resolution is (using pseudo code)):

    JPackageData.jpackageHome ?: defaultToolchainJavaHome(project)

This does not take into account the java home configured in the task itself. Resolution should work like this:

    JPackageData.jpackageHome ?: task.javaHome ?: defaultToolchainJavaHome(project)