Command Not Found behavior

[fallingrock]

The wiki has for version 3.4 has aa section on handling a command not found situation (https://docs.spring.io/spring-shell/reference/3.4/customization/commandnotfound.html).

That section does not exist in version 4 of the wiki.

Additionally, the CommandNotFoundMessageProvider class does not appear to exist in version 4.0.2 of spring shell.

[czpilar]

I looked into this a bit. The removal appears to be intentional rather than an oversight:

CommandNotFoundMessageProvider and CommandNotFoundResultHandler were removed in commit 7199ea4 ("Redesign command programming model"), together with the rest of the result-handler machinery. The corresponding documentation section was dropped as part of the 4.0 docs rewrite.

In 4.0.x, the behavior is now: CommandExecutor throws a CommandNotFoundException, which InteractiveShellRunner catches and handles with a hardcoded message ("Command %s not found" followed by the list of available commands).

There is currently no lightweight way to customize this message. The only option is to replace the entire ShellRunner bean (the auto-configured runners are @Conditional*), which is quite heavy-handed for changing a single message.

So the question for the @fmbenhassine is probably:

1. Should a customization hook be reintroduced, e.g. an overridable message-provider bean injected into the runners, similar in spirit to the 3.4 CommandNotFoundMessageProvider?
2. Or is the removal considered final, in which case it would be worth mentioning in the migration notes as a breaking change?