some changes

src/MaxWindowContact.ts

@@ -25,8 +25,12 @@ export class MaxWindowContact extends AHomematicItem {
     }
 
     processMessage(topic: string, payload: string) : void {
-        this.state = payload
+	if (payload == 'true') {
+		this.state = 'OPEN'
+	} else {
+		this.state = 'CLOSED'
+	}
         mqttHandler.send(this.stateFeedbackTopic, this.state)
     }
 
-}
+}