Question about failure result of get_target_property

I’m trying to troubleshoot an issue with a VS project generated by CMake. The relevant section of the cmake file is:

  get_target_property(test_suite_folder ${test_suite} FOLDER)
  if (NOT ${test_suite_folder} STREQUAL "NOTFOUND")
    set_property(TARGET ${test_name} PROPERTY FOLDER "${test_suite_folder}")
  endif ()

In my generated visual studio project, I see a folder test_suite_folder-NOTFOUND at the root. My gut tells me that get_target_property returns this when it fails, but the documentation (which surely the original author was writing against) for get_target_property states:

Non-inherited properties will set VAR to NOTFOUND

I know basically nothing about how the CMake internals work, but I found the following at line 90 of Source/cmGetTargetPropertyCommand.cxx:

mf.AddDefinition(var, var + "-NOTFOUND");

… which leads me to believe that the docs are incorrect. My question is: is this a documentation bug, or am I overlooking something?

it does not set NOTFOUND, it appends -NOTFOUND to the variable name.