implement Owners property validly

src/main/java/sensor2graph/Sensor.java

@@ -74,9 +74,14 @@ class Sensor {
 			"21.T11148/709a23220f2c3d64d1e1",
 			rec.get("sensor_type").asString()
 		);
-		add_attribute(body, "21.T11148/9a15a4735d4bda329d80",
+		add_attribute(body,
+			"21.T11148/9a15a4735d4bda329d80",
 			"https://sensor.community"
 		);
+		add_attribute(body,
+			"21.T11148/4eaec4bc0f1df68ab2a7",
+			"{\"Owners\":[{\"Owner\":{\"ownerName\":\"SensorCommunity\",\"ownerContact\":\"contact@open-forecast.eu\"}}]}"
+		);
 		Main.glogger.fine("sent body: " + body);
 
 		HttpRequest request = HttpRequest.newBuilder(URI.create(Main.pid_registry_uri + target_uri))