add log for no baggage in server interceptCall

Author: AgraVator

opentelemetry/src/main/java/io/grpc/opentelemetry/OpenTelemetryTracingModule.java

@@ -342,6 +342,9 @@ public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(ServerCall<ReqT, Re
       Baggage baggage = BAGGAGE_KEY.get();
       if (baggage != null) {
         serverCallContext = serverCallContext.with(baggage);
+      } else {
+        logger.log(Level.WARNING, "Server baggage not found, which is unexpected as "
+            + "it is being added unconditionally in filterContext().");
       }
       try (Scope scope = serverCallContext.makeCurrent()) {
         return new ContextServerCallListener<>(next.startCall(call, headers), serverCallContext);