code: @Override
      public ConnectionGroup getRootConnectionGroup()
              throws GuacamoleException {
          return new SimpleConnectionGroup(
              DEFAULT_ROOT_CONNECTION_GROUP,
              DEFAULT_ROOT_CONNECTION_GROUP,
              getConnectionDirectory().getIdentifiers(),
              Collections.<String>emptySet()
          );
      }
docs: {@inheritDoc}
  
  <p>This implementation returns a new {@link ConnectionGroup} with the
  identifier defined by {@link #DEFAULT_ROOT_CONNECTION_GROUP} and
  containing all connections exposed by the {@link Directory} returned by
  {@link #getConnectionDirectory()}. Implementations that wish to provide
  a structured connection hierarchy should override this function. If only
  a flat list of connections will be used, only
  {@link #getConnectionDirectory()} needs to be overridden.