initial commit
Add 'references/subproject/' from commit 'd07d019be4fa86f80ffd8f88b17075152992ecd2'

git-subtree-dir: references/subproject
git-subtree-mainline: 889a973a654adec91a8facf5456588df82ffba79
git-subtree-split: d07d019be4fa86f80ffd8f88b17075152992ecd2