Welcome to the forun Daniele.
First off, node-red uses JavaScript not Java, they are two different things.
It would be very helpful if you let us know what vrsion of Node-red and node.js you are using (you can get this from the startup log) and could export your flow and attach it to a reply so someone could actually see what you are doing. In order to make code more readable and importable it is important to surround your code with three backticks
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like this
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You can edit and correct your post by clicking the pencil icon.
See this post for more details - How to share code or flow json
