I would to try the export functionality of primefaces.
GO at /home.jsf and to sheet.jsf page. It works the export funcionality. But if i go at Maintenance/Customer/list page, the export not working.
I adapted the example from :
https://www.primefaces.org/showcase/ui/data/dataexporter/basic.xhtml i used the library name for the icons of pdf , or excel icon
Used: Wildfly server.
Important: for run the netbeans project, resolve the dependencies: from project right click and select properties/lib.
Into libs add the primefaces-6.1.jar and all-themes-1.0.10.jar (download from primefaces web site). Add also the the jtext-2.1.7.jar and poi-3.7.jar and xmlbeans-2.3.0 for exporting features.
For the persistence, control the name if your db is configurated into wildfly with same name: into project the persitence.xml contains: java:/jboss/datasources/MySQLDS