code: public String addAlias(String indice,String alias){
  		String aliasJson = new StringBuilder().append("{\"actions\": [{\"add\": {\"index\":\"").append(indice).append("\",\"alias\": \"").append(alias).append("\"}}]}").toString();
  		return this.client.executeHttp("_aliases",aliasJson,ClientUtil.HTTP_POST);
  	}
docs: Associating the alias alias with index indice
  more detail see :
  https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html
  @param indice
  @param alias
  @return