target/generated-sources/annotations/ generated by IDE is included in -sources.jar

### Affected version

3.3.1

### Bug description

see https://github.com/avaje/avaje-http/issues/650

not sure at all that there is a real bug in the plugin, or if it is default configuration, or...

but it's at least surprising that `sources-jar` contains a `target` directory, even if content is a concurrent IDE run

would be useful to understand what adds this content and if it would make sense to enhance defaults so that type of directories is not added, even if found on disk for strange reason (IDE parallel build in this case): better resiliency, more adverse events preparation
(notice: I don't want hacks, if we discover that there is a good reason for that result)