CMake BOOL生成器表达式将空列表评估为true的问题

我尝试在CMake构建中添加自定义命令目标，基于包含生成器表达式的变量追加参数列表，原始代码如下：

list(
  APPEND MY_INCLUDE_DIRECTORIES
    $<TARGET_PROPERTY:target,INCLUDE_DIRECTORIES>
    $<TARGET_PROPERTY:target,INTERFACE_INCLUDE_DIRECTORIES>
)

add_custom_target(
  custom_target
  COMMAND binary
    "$<$<BOOL:$<GENEX_EVAL:${MY_INCLUDE_DIRECTORIES}>>:--includes;$<JOIN:${MY_INCLUDE_DIRECTORIES},;--includes;>>"
  COMMAND_EXPAND_LISTS
  VERBATIM
)

但实际运行时，当MY_INCLUDE_DIRECTORIES评估为空列表时，仍会执行binary --includes。为了排查问题，我修改代码进行调试：

add_custom_target(
  custom_target
  COMMAND binary 
    "$<BOOL:$<GENEX_EVAL:${MY_INCLUDE_DIRECTORIES}>>"
    "$<GENEX_EVAL:${MY_INCLUDE_DIRECTORIES}>"
  COMMAND_EXPAND_LISTS
  VERBATIM
)

调试结果输出binary 1，这说明BOOL表达式评估为true，但实际列表是空的——我是否在操作上有误？

编辑：我已经找到修复方法，但仍不理解原因，修改后的代码如下：

list(
  APPEND MY_INCLUDE_DIRECTORIES
    "$<TARGET_PROPERTY:target,INCLUDE_DIRECTORIES>$<TARGET_PROPERTY:target,INTERFACE_INCLUDE_DIRECTORIES>"
)

内容的提问来源于stack exchange，提问作者Jazzwave06