tab completion with @ShellOption(value = "") does not work

[linux-china]

I want to implement tab completion for zk node name with following code:

 @ShellMethod(key = "cd", value = "Change Path")
public String cd(@ShellOption(help = "Directory", value = "", valueProvider = ZkPathValueProvider.class) String path) {

After input cd <caret>, and I press tab and nothing happened. If I input any other character alike cd x<caret> and tab completion works.

Is it a bug or I made mistake? or how to implement tab completion for path alike value?

Spring Shell version: 2.1.0-M2