I've been engaged as a scout leader in the Scout movement since 1993, working on a local and national level, leading both kids and other scout leaders.
Last year, the Swedish Scout Association invited 40000 scouts aged 14-17 years old from 150 countries around the world to go camping for 10 days. I was on the planning team with a couple of hundreds of my closest scout friends and during a couple of years we spent our spare time planning logistics, food, program, etc to give these youths an experience of a life time.
It was a big and complex project; different languages, religion (Ramadan was celebrated during the camp) and the Swedish weather were some of the factors we had to take into account. The camp was a huge success, the daily wow factor was measured and people truly had fun and got to know each other. I learnt a lot and got friends around the globe - looking back at the pictures it feels unreal that we managed it.
The Java platform as OpenJDK and its' future is a similar project in my mind. With 9 million developers and being installed on 3 bn devices, the platform touches a lot of users and businesses. There's a strong community taking Java into the future, making sure it stays relevant. Finding ways to collaborate in a scalable way is the key to success here. We have the bylaws directing how decisions are made, roles are appointed and how to "level" within the community. Using these, we can then make contributions according to our competence and interest and innovate taking our platform into the future.
If you find a way to organize volunteers towards a common goal, solving conflicts, making decisions, dividing the work into manageable chunks and having fun while doing it - there's no end to what you can achieve.