qdoc cannot find class in any header file

Suppose I have a file named class.h with some class Class in it and no source file. When documenting it in a *.qdoc file I get the following error:

someclass.qdoc:1: (qdoc) warning: Cannot find 'Class' specified with '\class' in any header file

I have noticed that by adding source file that includes the header makes qdoc to find the class. However if the header is not included (e.g. template class that is header-only and not used anywhere) it makes it impossible to document.

Attaching sample directory demonstrating the problem.