package com.nicklastrange.example import com.nicklastrange.Processor import com.nicklastrange.util.Helper class SampleService { Processor processor SampleService(Processor processor) { this.processor = processor } String process(String input) { def result = processor.transform(input) return Helper.clean(result) } private void reset() { processor.reset() } } interface Resettable { void reset() } class ExtendedService extends SampleService implements Resettable { ExtendedService(Processor processor) { super(processor) } void reset() { // no-op } }