The things that hold modifications back from being upstreamed are getting consensus with the OSS developers and sometimes the internal legal team. Occasionally,

The things that hold modifications back from being upstreamed are getting consensus with the OSS developers and sometimes the internal legal team. Occasionally, the issue is proprietary information. Usually, it's the time commitment or upstream not being interested. What companies don't like doing is maintaining patches on a fork, and that's enough incentive to give back on its own.