code: private HELM2Notation validate(String helm) throws ValidationException, ChemistryException {
  
  		try {
  			/* Read */
  			HELM2Notation helm2notation = readNotation(helm);
  
  			/* Validate */
  			LOG.info("Validation of HELM is starting");
  			Validation.validateNotationObjects(helm2notation);
  			LOG.info("Validation was successful");
  
  			return helm2notation;
  
  		} catch (MonomerException | GroupingNotationException | ConnectionNotationException | PolymerIDsException
  				| ParserException | JDOMException | IOException | NotationException
  				| org.helm.notation2.parser.exceptionparser.NotationException e) {
  			e.printStackTrace();
  			LOG.info("Validation was not successful");
  			LOG.error(e.getMessage());
  			throw new ValidationException(e.getMessage());
  		}
  	}
docs: method to validate the HELM-String input
  
  @param helm
  input HELM string
  @return ContainerHELM2
  @throws ValidationException
  if the HELM input is not valid
  @throws ChemistryException
  if the Chemistry Engine can not be initialized
  @throws NotationException