implement valid LandingPage

src/main/java/sensor2graph/Main.java

@@ -250,18 +250,17 @@ public class Main {
 		Map<String, Object> parameters = new Gson().fromJson(new FileReader("sensor_type_info.json"), new TypeToken <Map<String, Object>>() {}.getType());
 		try (var session = Main.driver.session(SessionConfig.forDatabase(Main.database_name))) {
 			session.writeTransaction(tx -> {
-				Result res = tx.run(
+				tx.run(
 					"unwind $sensor_type_info as sensor_type_info\n" +
 					"merge (n:SensorType {sensor_type: sensor_type_info.props.sensor_type})\n" +
 					"set n = sensor_type_info.props\n" +
 					"with n, sensor_type_info\n" +
 					"unwind sensor_type_info.measured_variables as measured_variable\n" +
 					"merge (m:MeasuredVariable {variable: measured_variable})\n" +
-					"merge (n)-[:MEASURES]->(m)\n" +
-					"return 1",
+					"merge (n)-[:MEASURES]->(m)\n",
 					parameters
 				);
-				return 5;
+				return 42;
 			});
 		}
 	}

src/main/java/sensor2graph/Sensor.java

@@ -74,6 +74,9 @@ class Sensor {
 			"21.T11148/709a23220f2c3d64d1e1",
 			rec.get("sensor_type").asString()
 		);
+		add_attribute(body, "21.T11148/9a15a4735d4bda329d80",
+			"https://sensor.community"
+		);
 		Main.glogger.fine("sent body: " + body);
 
 		HttpRequest request = HttpRequest.newBuilder(URI.create(Main.pid_registry_uri + target_uri))