code: public Observable<Void> createAsync(String personGroupId, CreatePersonGroupsOptionalParameter createOptionalParameter) {
          return createWithServiceResponseAsync(personGroupId, createOptionalParameter).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Create a new person group with specified personGroupId, name and user-provided userData.
  
  @param personGroupId Id referencing a particular person group.
  @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.