Developers.google  is Google's site for software development tools, application programming interfaces, and technical resources. The site contains documentation on using Google developer tools and APIs—including discussion groups and blogs for developers using Google's developer products. Not a lot of recruiters try to source there. The reason is simple they do not know how. Well to do this without worry you need go no further than into your bag of tricks and pull out an old tried and true tool, a simple search with some extras

So to source within Code.Google you simply need to use a skill known as xraying, like the one below. Now the interesting thing is this will actually be a Github results once you open the pages.

site:developers.google.com/ (directory OR Profile OR gmail OR "mailing LIst") 

If you run the strings above in google you will get the results below.

Notice the 3^rd results down and guess what it is? A Directory of active members

If you need more info on X-raying see my blog post

http://www.recruitingblogs.com/profiles/blogs/seeing-what-is-really...

See my YouTube video on x-raying

http://bit.ly/2SItz9m