toOptional
Wrap this single converter with a SingleToOptionalConverter, which is a special converter that will act like an OptionalConverter using the same logic of this converter.
Your converter should be designed with this pattern in mind. If that's not possible, please override this function and throw an exception in the body.
For more information on the parameters, see Converter.
Parameters
Optionally, a signature type string to use instead of the one this converter provides.
Optionally, override this converter's setting for showing the type string in a generated command signature.
Optionally, a longer type string to be shown in errors instead of the one this converter provides.
Optionally, provide true to fail parsing and return errors if the converter throws a DiscordRelayedException (instead of continuing).