Having findbug running against generated code is a problem because you'll have so many pointless warnings and errors that you might miss the real ones. The ones you can really do something about.

To exclude a package from the repports you'll have to create a exclution filter file usualy name findbugs-exclude.xml
<Package name="~org.sinarf.myapp.mygeneratedpackage.*" />

Filter documentation should contain anything you would need : Chapter 8. Filter Files.

Maven should be informed that it should use a filter exclude file.