Under --automation-read-root, document.inspect gives `path` as null when
the document's file is outside the read roots. document.json names a
linked image or placed file outside them by its file name alone, without
its relative path, size or date, in the layers, symbols, graph designs,
patterns, the pattern being edited and opacity masks. It also names a
data set's image value outside them by its file name, and leaves the
Export for Screens folder outside them out of export_settings. The
document is not changed, and unconfined callers see the same replies as
before.