While starting managed channels on client we get error: `Channel for target was not shutdown properly!!!` about karate-grpc

[thinkerou]

grpc-java ref: grpc/grpc-java#4032

[thinkerou]

If have not call onNext will occur the error, like:

    @Override
    public StreamObserver<RouteNote> routeChat(final StreamObserver<RouteNote> responseObserver) {
        return new StreamObserver<RouteNote>() {
            @Override
            public void onNext(RouteNote routeNote) {
                List<RouteNote> notes = getOrCreateNotes(routeNote);

                for (RouteNote preNote : notes.toArray(new RouteNote[0])) {
                    // HERE:
                    // If not arrive here, it will error.!!!!
                    responseObserver.onNext(preNote);
                }

                notes.add(routeNote);
            }

            @Override
            public void onError(Throwable throwable) {
                logger.warning("RouteChat cancelled");
            }

            @Override
            public void onCompleted() {
                responseObserver.onCompleted();
            }
        };
    }