Mapper attachment not working


I am tryng a very simple code to search on attachment file but I have no result for my query.
To semplify my test I have replicate exactly the code on the plugin page:

I follow step by step the code on "Querying or accessing metadata" paragraph but it doesn't return any match.

The plugin is correctly installed and a simple _search in the index works (I see Base64 file).

Can you help me?


The version of mapper-attachment plugin was wrong!