Dirk Riehle, a software engineering professor, writes about open source business models, licensing, and research on open source development practices.
HN commenters link it for his work on single-vendor commercial open source, the Java IP story, and his study of paid versus volunteer open source work.
Let's be clear, this isn't left-pad we are talking about - these are MASSIVE projects which are in some cases 16+ years old. Personally, I find the fastest way to get up to speed is on projects of this size is to usually jump into IRC, find a mentor and start sending in documentation patches. Here the engineers for the runtime, framework, compiler teams are hanging out in Gitter and engaging with the community out in the open instead of being hidden behind closed doors. Why would you ignore an opportunity like that? They are there soliciting the advice from the community and if the there is no uptake/reciprocal energy then that's a problem. I agree on RTFM but at this stage, there is minimal documentation for the majority of these projects and that internal domain knowledge needs to be dispersed into the community. Code only tells you about the implementation, it does not tell you about the why and information about trade-offs which were made.
http://dirkriehle.com/publications/2014-2/the-five-stages-of-open-source-volunteering/
It can't be called Java unless it passes the TCK. Even so, it only gets a limited trademark license unless you're a paying customer of Oracle. Well fine, without licensing then passing the TCK, you can't call it Java, so what?
Well, since you're foregoing certification, even if you're deriving substantially from the OpenJDK, you're also foregoing the automatic patent grants. And since it's GPLv2, not GPLv3, Oracle or any of the companies who collaborated in the patent licensing scheme, is now free to sue you for billions or trillions.
So no, OpenJDK has a field-of-use restriction in that the only way for a company to build a successful product (or even a failed one) based on it and not get sued into oblivion is to license and pass the TCK to get the license for trademarks and protection for patents.
Here's a link which should prove informative: http://dirkriehle.com/2011/06/30/the-java-ip-story/
I'd argue that money's been in OSS since its inception.
To try to put a number on it, here's a random study that 50% of oss is people at their paid job: https://dirkriehle.com/2013/08/22/paid-vs-volunteer-work-in-open-source/
But anecdotally that number is consistent with my experience.
When we created the GNOME Foundation in 2000, it was in part to manage the commercial vendors and money involved (Compaq, Eazel, Helix Code, IBM, Sun Microsystems and VA Linux Systems, see the press release https://www.gnome.org/press/2000/08/red-hat-joins-industry-vendors-as-a-founding-member-of-the-gnome-foundation/).
This was not at all unique to GNOME, same kinda stuff around all the major projects at that time.
One thing I think is new and constructive is more ways to pay maintainers without asking them to join a giant company.
I hope single-vendor commercial open source business model would be more common. http://dirkriehle.com/publications/2009-2/the-commercial-open-source-business-model/
GPL + Commercial dual licensing seems to be really good option for small and midsize business where ake the code and take the business is real possibility. GPL is widely known and quite clear. GPL establishes open source genealogy, not just one point in time event like BSD licenses do.
Ghostscript, MySql, Qt etc. followed this path successfully. Qt is now a public company with open source product.
#5 seems like a very poor reason, but it depends on what your goals are.
I liked this story a lot: http://news.ycombinator.com/item?id=2728167 (or, direct link: http://dirkriehle.com/2011/06/30/the-java-ip-story/)
If you're fine with using a tightly-controlled, patent-littered language environment, then yeah, Java is great! :D
It's back up at http://dirkriehle.com - the project site is actually http://sweble.org where under Crystalball Demo you can play with the parser without having to install anything.