code: public void addHostAlias(String virtualHost, String alias)
      {
          log.warn("addHostAlias is deprecated. Use HttpContext.addVirtualHost");
          Object contextMap=_virtualHostMap.get(virtualHost);
          if (contextMap==null)
              throw new IllegalArgumentException("No Such Host: "+virtualHost);
          _virtualHostMap.put(alias,contextMap);
      }
docs: Define a virtual host alias.
  All requests to the alias are handled the same as request for
  the virtualHost.
  @deprecated Use HttpContext.addVirtualHost
  @param virtualHost Host name or IP
  @param alias Alias hostname or IP