Graylog exctractor specify timezone other than UTC

[mpolitaev (Mihail Politaev)]

For check timezone in date in timestamp field i should look into field value, but which function can do this? I found function “has_field” but it is check only if field present. Filed “timestamp” present for all messages, i need sort those who has format “dd/MMM/yyyy HH:mm:ss” and not change other like “dd/MMM/yyyy HH:mm:ss Z”