Add json indies another json when uploading data to ES

When uploading data to ES i need to have a json structure like

	"Countries" : {
		"Asia" : {
			"name" : "Srilanka"
		},
		"Africa" : {
			"name" : "Kenya"
		}
	}

Aggregate inside Aggregate.

is it possible to do this in logstash out put plhgin