"product" property not accessible from cpp.setupRunEnvironment Property

I want to add a path to external .dll files into "PATH" environment variable. I use setupRunEnvironment Property for it:

import qbs 1.0
StaticLibrary  {
     ...
    Export {
        Depends { name: "cpp" }

        cpp.setupRunEnvironment: {
            var v = new ModUtils.EnvironmentVariable("PATH", ";", true);
            v.prepend(product.sourceDirectory + "/dll" );
            v.set();
        }
    }
}

Seems "product" property not accessible from this fragment.
I got a error message: "Error retrieving run environment: ...\example_setupRunEnvironment\lib\lib.qbs:14:34 Error while setting up run environment: ReferenceError: Can't find variable: product"

I prepared and attached a small example project.