CMake Error at .*/Modules/ExternalData.cmake:[0-9]+ \(message\):
  Data file referenced by argument

    DATA{Directory1}

  corresponds to source tree path

    Directory1

  that is directory instead of a file!
Call Stack \(most recent call first\):
  .*
  Directory1\.cmake:[0-9]+ \(ExternalData_Add_Test\)
  CMakeLists\.txt:[0-9]+ \(include\)
