Method not available on this version
This method is only available on newer versions.
The first available version (v2_6_3) is shown here.
app_cache_dirname()
public
Name of directory where plugin the is expected to cache the gems when #cache is called.
Also this name is matched against the directories in cache for pruning
This is used by `app_cache_path`
# File lib/bundler/plugin/api/source.rb, line 172
def app_cache_dirname
base_name = File.basename(URI.parse(uri).normalize.path)
"#{base_name}-#{uri_hash}"
end