Export not transitive

app
|- main.cpp

lib1
|- lib.cpp

lib2
|- lib.cpp
|- Test.h


=== app-and-lib.qbs
import qbs 1.0

Project {
    references: [
        "app/app.qbs",
        "lib1/lib1.qbs",
        "lib2/lib2.qbs"
    ]
}

=== app.qbs
import qbs 1.0

Product {
    type: "application"
    name : "app-and-lib-app"
    files : [ "main.cpp" ]
    Depends { name: "cpp" }
    Depends { name: "lib1" }
}

=== lib1.qbs
import qbs 1.0

Product {
    type: "staticlibrary"
    name: "lib1"
    files: [ "lib.cpp" ]
    cpp.defines: ['CRUCIAL_DEFINE']
    Depends { name: 'cpp' }
    Depends { name: "lib2" }
}

=== lib2.qbs
import qbs 1.0

Product {
    type: "staticlibrary"
    name: "lib2"
    files: [
        "Test.h",
        "lib.cpp",
    ]
    cpp.defines: ['CRUCIAL_DEFINE']
    Depends { name: 'cpp' }

    Export {
      Depends { name: "cpp" }
      cpp.includePaths: "."
    }
}

=== lib.cpp
#include <stdio.h>
#include "Test.h"


#ifndef CRUCIAL_DEFINE
#   error CRUCIAL_DEFINE not defined
#endif

int bla()
{
    puts("Hello World!");
    return 2;
}

=== main.cpp
#include <stdio.h>
#include "Test.h" // Error cannot found Test.h

int bla();
int main()
{
  Test t = new Test();
    return bla();
}