Git Trees API without path parameter!

Git Trees

param: owner repo sha(ref) GET /repos/:owner/:repo/git/trees/:sha

The API only get root dir. but the sub directory can not get tree list. Here is github api:

param: owner repo ref path https://api.github.com/repos/${owner}/${repo}/git/trees/${ref}${path.replace(/^\//, ':')}

it can not get a sub-tree.