What is the essence of gypsy jazz?
I know this kind of question is unfashionable and often considered impertinent or useless, which is precisely why I'm asking it.
Is its essence a set of techniques? A set of tunes? A stylistic approach? How would you describe it?
Also, what things dilute its essence, or prevent it from flourishing?
(Please don't post the usual nonsense about "there being no single essence, you're being mean by even asking, waah!" We already know that. This question is designed to get some discussion going, not to clamp anything down.)