@Override
            public ParseResult parsePath(String path) {
              String root = null;
              if (path.matches("^[/$!].*")) {
                root = path.substring(0, 1);
                path = path.substring(1);
              }
              return new ParseResult(root, Splitter.on('/').omitEmptyStrings().split(path));
            }
This path service is for unix-like paths, with the exception that it recognizes $ and ! as
roots in addition to /, allowing for up to three roots. When creating a {@linkplain
PathType#toUriPath URI path}, we prefix the path with / to differentiate between a path like
"$foo/bar" and one like "/$foo/bar". They would become "/$foo/bar" and "//$foo/bar"
respectively.
jimfs/src/test/java/com/google/common/jimfs/FileTreeTest.java