Add optional String validateSettings(Map<String, String> propertiesMap) method too ActionHook

[kschmiechen]

To avoid invalid settings, the interceptor manager could call an optional method String validateSettings(Map<String, String> propertiesMap) of the hook each time its settings are updated in the administration panel. The method returns null if the settings are valid and a message if the settings are invalid.

[Jumas]

Hello Kevin, thanks for the idea.
It is implemented with the small change in the method signature.