@Override
    public void getBlogPost(GetBlogPostRequest request, StreamObserver<BlogPost> responseObserver) {
        final BlogPost blogPost = blogPosts.get(request.getId());
        if (blogPost == null) {
            throw new BlogNotFoundException("The blog post does not exist. ID: " + request.getId());
        } else {
            responseObserver.onNext(blogPost);
            responseObserver.onCompleted();
        }
    }
Retrieves a {@link BlogPost} whose {@link BlogPost#getId()} is the {@link GetBlogPostRequest#getId()}.
examples/tutorials/grpc/src/main/java/example/armeria/server/blog/grpc/BlogService.java