[jjav]

> I'm not suggesting a real obligation, but there is... something?

The only something there is, is what the license specifies.

Licenses vary, but generally the gist of it is that you get to use that code for free (with various limitations depending on license) and that's all you get. There isn't any something beyond that.

You're always free to negotiate and pay for a support contract if you prefer more than what the open source license grants you.