[striking]

I do, actually. It looks like a standard CLA. It grants them a perpetual license to whatever code you're contributing and allows them to use it as they please, and not affecting any of your other rights. There's also some stuff in there about you only contributing code that you actually have the right to contribute, and how to manage edge cases around that. It's fairly standard when someone intends to be able to use your contribution as part of a greater open-core / closed-source distribution and to be able to simplify licensing matters. They have to protect their own interests and they're doing so in a manner that basically doesn't affect you at all.

Do you hire a lawyer any time you encounter an unfamiliar OSS license? I assume you don't, or you'd have a hard time using any modern packaging ecosystem.