@Override
    public void request(int numMessages) {
        if (ctx.eventLoop().inEventLoop()) {
            request0(numMessages);
        } else {
            ctx.eventLoop().execute(() -> request0(numMessages));
        }
    }
Encapsulates the state of a single server call, reading messages from the client, passing to business logic
via {@link ServerCall.Listener}, and writing messages passed back to the response.
grpc/src/main/java/com/linecorp/armeria/server/grpc/StreamingServerCall.java