Use icinga event timestamp within icinga target

_meta/fields.yml

@@ -2,10 +2,6 @@
   title: icingabeat
   description: Data received from the Icinga 2 API
   fields:
-    - name: timestamp
-      type: date
-      description: >
-        Timestamp of event occurrence
 
     - name: type
       type: keyword

beater/eventstream.go

@@ -83,7 +83,7 @@ func BuildEventstreamEvent(e []byte) beat.Event {
 	}
 
 	event.Fields.Put("type", "icingabeat.event."+strings.ToLower(icingaEvent["type"].(string)))
-	event.Fields.Put("timestamp", FloatToTimestamp(icingaEvent["timestamp"].(float64)))
+	event.Fields.Put(target_key+"timestamp", FloatToTimestamp(icingaEvent["timestamp"].(float64)))
 
 	return event
 }

docs/fields.asciidoc

@@ -3477,16 +3477,6 @@ example: stretch
 Data received from the Icinga 2 API
 
 
-*`timestamp`*::
-+
---
-Timestamp of event occurrence
-
-
-type: date
-
---
-
 *`type`*::
 +
 --

fields.yml

@@ -2423,10 +2423,6 @@
   title: icingabeat
   description: Data received from the Icinga 2 API
   fields:
-    - name: timestamp
-      type: date
-      description: >
-        Timestamp of event occurrence
 
     - name: type
       type: keyword