For Windows platforms, even if I specify a "custom script", the plugin attempts to execute 'sh' with a path to my .bat file, which fails like so:

java.io.IOException: Cannot run program "sh" (in directory "C:\Program Files (x86)\Jenkins\jobs\echo_test\workspace"): CreateProcess error=2, The system cannot find the file specified

If the plugin simply added another category for Windows Batch scripts, the plugin could instead execute "cmd /c call <path/to/file.bat>".