docs: public void setEnabled( final boolean enabled ) throws IllegalStateException {
          if ( !enabled && !_sticky ) {
              throw new IllegalStateException( "Disabling this session manager is not allowed in non-sticky mode. You must switch to sticky operation mode before." );
          }
          final boolean changed = _enabled.compareAndSet( !enabled, enabled );
          if ( changed && _manager.isInitialized() ) {
              reloadMemcachedConfig( _memcachedNodes, _failoverNodes );
              _log.info( "Changed enabled status to " + enabled + "." );
          }
      }