https://github.com/jenkinsci/extended-choice-parameter-plugin/blob/master/src/main/java/com/cwctravel/hudson/plugins/extended_choice_parameter/ExtendedChoiceParameterDefinition.java#L427

should implement @DataboundConstructor to support snippet generator. Or a new constructor should be supplied allowing for some sensible defaults. Just an idea.

Usage with pipeline is currently possible but not very practical. The number of parameters required for the current constructor is pretty huge.