Add gRPC stream client example for java

[zhansg]

I've added an example implementation of a gRPC stream client in Java to enhance the utility for those new to gRPC.

Additionally, I've writed code for converting gRPC client to SSE interfaces api and wondering if it would be suitable for this repository. Please let me know if you would like me to include it.

Your feedback on the code would be greatly appreciated.

Thanks Best regards