code: public boolean addAttachment(Attachment attachment) {
      boolean isExist = false;
      for (Attachment a : attachmentList) {
        if (a.getLabel().equalsIgnoreCase(attachment.getLabel())) {
          isExist = true;
        }
      }
      if (!isExist) {
        return attachmentList.add(attachment);
      }
      return false;
    }
docs: Try to add a new attachment to this monomer
  
  @param attachment -- new attachment to be add in
  @return true for success and false if there is one such attach point exist