code: @Override
      public String getUserSecurityName(String uniqueUserId) throws EntryNotFoundException, RegistryException {
          if (uniqueUserId == null) {
              throw new IllegalArgumentException("uniqueUserId is null");
          }
          if (uniqueUserId.isEmpty()) {
              throw new IllegalArgumentException("uniqueUserId is an empty String");
          }
  
          if (!isValidUser(uniqueUserId)) {
              throw new EntryNotFoundException(uniqueUserId + " does not exist");
          }
          return uniqueUserId;
      }
docs: {@inheritDoc}