As some plugins are becoming big now, it is hard for the user to know, if the plugin
is being downloaded or just nothing happens.
This commit adds a progress bar during download, which can be disabled by using the `-q`
parameter.
In addition this updates to jimfs 1.1, which allows us to test the batch mode, as adding
security policies are now supported due to having jimfs:// protocol support in URL stream
handlers.
This fixes the `lenient` parameter to be `missingClasses`. I will remove this boolean and we can handle them via the normal whitelist.
It also adds a check for sheisty classes (jar hell with the jdk).
This is inspired by the lucene "sheisty" classes check, but it has false positives. This check is more evil, it validates every class file against the extension classloader as a resource, to see if it exists there. If so: jar hell.
This jar hell is a problem for several reasons:
1. causes insanely-hard-to-debug problems (like bugs in forbidden-apis)
2. hides problems (like internal api access)
3. the code you think is executing, is not really executing
4. security permissions are not what you think they are
5. brings in unnecessary dependencies
6. its jar hell
The more difficult problems are stuff like jython, where these classes are simply 'uberjared' directly in, so you cant just fix them by removing a bogus dependency. And there is a legit reason for them to do that, they want to support java 1.4.
Yannick Welsch
Nik Everett
Alexander Reelsen
Robert Muir