Java is open source too and C# is not the only corporate language from MicroSoft.
So yes, just because it's open source doesn't mean much, but it's open source with a very liberal license, which does mean something.
A pure BSD license does not have these restrictions.
Now, in this particular case (for those who can digest legalease): http://golang.org/PATENTS
[0]: https://en.wikipedia.org/wiki/Java_(software_platform)#Free_...
Nothing against Java, now, but it's not a fair comparison to Go. (Disclosure: I was an early Go contributor but no longer use it for day to day work. I have no affiliation with Google.)
[0]: https://en.wikipedia.org/wiki/Java_(software_platform)#Free_...