code: @Override
      public boolean isValidGroup(String groupSecurityName) throws RegistryException {
          if (groupSecurityName == null) {
              throw new IllegalArgumentException("groupSecurityName is null");
          }
          if (groupSecurityName.isEmpty()) {
              throw new IllegalArgumentException("groupSecurityName is an empty String");
          }
  
          return state.groups.containsKey(groupSecurityName);
      }
docs: {@inheritDoc}