@Override
        public void write(ByteBuffer buf, CompletionHandler handler) {
            buffers.add(buf);
            if (handler != null) handler.completed();
        }
A handler which returns state (health) information from this container instance: Status, metrics and vespa version.

@author Simon Thoresen Hult
container-core/src/main/java/com/yahoo/container/jdisc/state/StateHandler.java