code: private OntologyTermSynonym createSynonym(String synonym) {
      OntologyTermSynonym entity = ontologyTermSynonymFactory.create();
      entity.setId(idGenerator.generateId());
      entity.setOntologyTermSynonym(synonym);
      synonymRepository.add(entity);
      return entity;
    }
docs: Creates an {@link OntologyTermSynonymMetadata} {@link Entity} and adds it to the {@link
  #synonymRepository}.
  
  @param synonym String of the synonym to create an {@link Entity} for
  @return the created {@link Entity}