code: public Docket additionalModels(ResolvedType first, ResolvedType... remaining) {
      additionalModels.add(first);
      additionalModels.addAll(Arrays.stream(remaining).collect(toSet()));
      return this;
    }
docs: Method to add additional models that are not part of any annotation or are perhaps implicit
  
  @param first     - at least one is required
  @param remaining - possible collection of more
  @return on-going docket
  @since 2.4.0