Yes you read it right! Microsoft officially announced on the “Connect()” event for .NET programming model plans and they are going to open source .NET. According to the officials, they have plans to open source full server side .NET core stack and port that open-sourced part to Linux, Mac OS X and of-course Windows.
However, Microsoft is not planning to open source the client side technologies such as Windows Forms, WPF for now.
You can find the source code here: github.com/dotnet/corefx
And it probably beginning of the end of for Java. Lets wait and see.