code: public Set<String> getSupportedApplicationIds() {
          final AlexaApplication app = this.getClass().getAnnotation(AlexaApplication.class);
          return app != null ? Stream.of(app.applicationIds()).collect(Collectors.toSet()) : Collections.emptySet();
      }
docs: Provides a set of application-id(s) you can find in the Alexa developer console of your skill.
  Only requests coming in with these application-id(s) pass the request verification.
  @return supported application ids