Dick,
This is a discussion forum.
You are the first one to mention DEFINITION on this thread which contains some interesting discussion.

Obviously 'folk song' has now got many differing meanings to different people. My perception of the OP's question is he is asking if the song was collected from oral tradition or was it purposely rewritten for Tin Pan Alley. I for one am happy that the question has been answered perfectly well.

Dick, you are perfectly entitled to your opinion, but the impression I get from others on the thread is that you are on your own.