xpath.ToGNMIPath() fails for a xpath string that contains square brackets in key value

[pkbehera]

x_path := '/a/b[id=foo][res=/bar/tar[name=xx]]/cfg'

gpath, err := xpath.ToGNMIPath(x_path)

// err = invalid path element b[id=foo][res=/bar/tar[name=xx]]: malformed List key-value pair string: [id=foo][res=/bar/tar[name=xx]]

Yang specification does not seem to prohibit use of [ or ] in the key-value pairs. ALSO I am able to add an element to a gnmi.Path with key-value pairs containing [ or ] or both