Explain how metadata can be accessed at the server side

[derolf]

Using the reactor version with Kotlin, a simple example how to get access to the metadata (headers) is possible inside the service call.

[rmichela]

Similar to #56

[derolf]

Is it correct just to use io.grpc.Context like in:

https://github.com/salesforce/reactive-grpc/blob/master/reactor/reactor-grpc-test/src/test/java/com/salesforce/reactorgrpc/ContextPropagationIntegrationTest.java

?

[cbornet]

Yes that's the way to do it. In the server interceptor, get the value from Metadata then put it in Context.

[rmichela]

@derolf Were we able to answer your question? If not, please re-open this issue. 😁

[derolf]

As said, putting a paragraph in the docs would be nice...

[cbornet]

Oh, and you need to put the gRPC context in the Reactive sequence context !
As said by @rmichela this is the same as #56