Hi,

while request trends data and query via "output":"value_max", it show no data.

The doc https://www.zabbix.com/documentation/4.0/manual/api/reference/trend/get say:

"

"

So, I want get "value_max" data only. Is it bug or feature?

Thanks

Steps to reproduce:

1. [localhost ~]$ json='{"jsonrpc":"2.0","method":"trend.get","params":{"itemids":"230188","time_from":"1554066000","time_till":"1556658000","output":"extend", "limit":1},"id":"1","auth":"da4cbc142231d9f062a1e3f0a08d158d"}'
   [localhost ~]$ curl -w '\n' -s -X POST -H 'Content-Type: application/json-rpc' -d "$json"  http://localhost/zabbix/api_jsonrpc.php
   {"jsonrpc":"2.0","result":[\{"itemid":"230188","clock":"1554066000","num":"60","value_min":"3.5717","value_avg":"6.7835","value_max":"14.2263"}],"id":"1"}

[localhost ~]$ json='{"jsonrpc":"2.0","method":"trend.get","params":{"itemids":"230188","time_from":"1554066000","time_till":"1556658000","output":"value_max", "limit":1},"id":"1","auth":"da4cbc142231d9f062a1e3f0a08d158d"}'
[localhost ~]$ curl -w '\n' -s -X POST -H 'Content-Type: application/json-rpc' -d "$json"  http://localhost/zabbix/api_jsonrpc.php                                                                                     {"jsonrpc":"2.0","result":[[]],"id":"1"}
[localhost ~]$

Result:

empty response

Expected:
value in response