Problem/Motivation
This is a follow up to #2925899: MigrateUpgradeImportBatch does not use source_private_file_path & source_base_path correctly, making it impossible to have public & private files in separate locations.
In that issue benjifisher stated,
The current form suggests (at least to me) that the files will be directly under bar/, when they are actually under bar/sites/default/files/.
Let's review the help text and make sure it is clear to everyone where the files need to be. Use the description in the makeFiles method from the patch in 2925899-Comment#39 for inspiration.
For reference here are the current descriptions:
Public files
To import public files from your current Drupal site, enter a local file directory containing your site (e.g. /var/www/docroot), or your site address (for example http://example.com).
Private files
To import private files from your current Drupal site, enter a local file directory containing your site (e.g. /var/www/docroot).
Proposed resolution
TBD