Error when no list

[ferdymercury]

I get an error:

CMake Error at make_documentation.cmake:233 (list):
  list sub-command SORT requires list to be present.
Call Stack (most recent call first):
  make_documentation.cmake:274 (WRITE_CMAKE_DOCUMENTATION)
  CMakeLists.txt:15 (include)

This can be fixed by:

        if(gPROCESS_CMAKE_DOCUMENTATION_FILES_LIST)
            list(SORT   gPROCESS_CMAKE_DOCUMENTATION_FILES_LIST)
        endif()
        if(gPROCESS_CMAKE_DOCUMENTATION_FILES_DESCRIPTIONS)
            list(SORT   gPROCESS_CMAKE_DOCUMENTATION_FILES_DESCRIPTIONS)
        endif()
        if(gPROCESS_CMAKE_DOCUMENTATION_SECTION_LIST) 
            list(SORT   gPROCESS_CMAKE_DOCUMENTATION_SECTION_LIST)
        endif()
        if(gPROCESS_CMAKE_DOCUMENTATION_SECTION_CONTENT)
            list(SORT   gPROCESS_CMAKE_DOCUMENTATION_SECTION_CONTENT)
        endif()