It's must to have a dummy qml file when creating a QML type from C++ in the module

I'm wondering if it's possible to create a QML type without having any qml file in the module.
In the attached project, I have CppModule module which is defined in cppmodule.qmlproject.
 
The issue is, when I don't have any qml files specified as QmlFiles.files in cppmodule.qmlproject, the "loader_item_allocator.cpp" doesn't get generated and the application compilation fails.

// error. The Japanese line says "cannot open the source file"

c1xx: fatal error C1083: ソース ファイルを開けません。'C:\work\MCU_Training_Material\Training_Repos\GeneralPlus\GeneralPlus\1_1_QML\07_Modules\build\qmlproject\CMakeFiles\Modules.dir\CppModule\loader_item_allocator.cpp':No such file or directory 

But when I just created dummy.qml and set it to QmlFiles.files, the application compiled successfully. This made me wonder if I'm missing something.
The attached project can be built with Qt for MCUs 2.5 - Desktop 32bpp (MSVC)