code: public Observable<Void> createAsync(String faceListId, CreateFaceListsOptionalParameter createOptionalParameter) {
          return createWithServiceResponseAsync(faceListId, createOptionalParameter).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Create an empty face list. Up to 64 face lists are allowed to exist in one subscription.
  
  @param faceListId Id referencing a particular face list.
  @param createOptionalParameter the object representing the optional parameters to be set before calling this API
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceResponse} object if successful.