code: @Override
      public boolean isValidUser(String userSecurityName) throws RegistryException {
          if (userSecurityName == null) {
              throw new IllegalArgumentException("userSecurityName is null");
          }
          if (userSecurityName.isEmpty()) {
              throw new IllegalArgumentException("userSecurityName is an empty String");
          }
          return user.equals(userSecurityName);
      }
docs: {@inheritDoc}