code: @Nonnull
  	public String createSessionId( @Nonnull final String sessionId ) {
  		return isEncodeNodeIdInSessionId() ? _sessionIdFormat.createSessionId(sessionId,  _nodeIdService.getMemcachedNodeId() ) : sessionId;
  	}
docs: Creates a new sessionId based on the given one, usually by appending a randomly selected memcached node id.
  If the memcachedNodes were configured using a single node without nodeId, the sessionId is returned unchanged.