That's because this sample was just pulled from the BlazeDS source distribution (available here) and modified. This is why I've just included the sample in my blog post and not as part of our official M1 distribution. We will likely include a more integrated Spring-branded sample with our distribution in the future.
For now, if you want to be able to build everything I'd suggest pulling down the BlazeDS source distro and merging my changes back into that directory structure.
Staff Engineer, Web Products Team