code: public Elasticsearch host(String hostname, int port, String protocol) {
  		final Host host =
  			new Host(
  				Preconditions.checkNotNull(hostname),
  				port,
  				Preconditions.checkNotNull(protocol));
  		hosts.add(host);
  		return this;
  	}
docs: Adds an Elasticsearch host to connect to. Required.
  
  <p>Multiple hosts can be declared by calling this method multiple times.
  
  @param hostname connection hostname
  @param port connection port
  @param protocol connection protocol; e.g. "http"