Elasticsearch documentation page states that supported value types for history storage are uint,dbl,str,log,text. Also the same types are used as examples in zabbix_server.conf and zabbix.conf.php.example files. This does not exactly match the types which are set by default on the server - src/zabbix_server/server.c:zbx_set_defaults().

CONFIG_HISTORY_STORAGE_OPTS = zbx_strdup(CONFIG_HISTORY_STORAGE_OPTS, "unum,float,char,log,text");