code: @Override
  	public void close() throws IOException {
  		if (this.client != null)
  			this.client.close();
  		indexCache.clear();
  		indexCache = null;
  		updatePolicy = null;
  		insertPolicy = null;
  		infoPolicy = null;
  		queryPolicy = null;
  		moduleCache.clear();
  		moduleCache = null;
  	}
docs: closes the QueryEngine, clearing the cached information are closing the AerospikeClient.
  Once the QueryEngine is closed, it cannot be used, nor can the AerospikeClient.