Current workflow plugin does not support checking the progress of file transfer when running in workflow scripts. If we are to copy same files to various slaves, with different connection speed. It will be a very long wait and not knowing what's the progress of the copy goes.
Please add a progress bar during this stash/unstash process. It can be a simple text printed representing the percentage. Currently without this progress bar, we are using wget command which does download the file and give the progress bar. But this will only works if the file is located in a container webapps context, and kind of separated out the file from the Workflow Workspace which is the main idea of the Workflow plugin.