Support generating autocompletion scripts for non-public @Command classes #306
Description
Problem
When following the instructions at http://picocli.info/autocomplete.html to generate a bash completion script for a non-public @Command class, picocli.AutoComplete throws the following exception:
java.lang.IllegalAccessException: Class picocli.AutoComplete$App can not access a member of class bisq.cli.Bisq with modifiers ""
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
at java.lang.Class.newInstance(Class.java:436)
at picocli.AutoComplete$App.run(AutoComplete.java:89)
at picocli.CommandLine.execute(CommandLine.java:775)
at picocli.CommandLine.access$700(CommandLine.java:139)
at picocli.CommandLine$RunLast.handle(CommandLine.java:998)
at picocli.CommandLine$RunLast.handle(CommandLine.java:966)
at picocli.CommandLine$AbstractParseResultHandler.handleParseResult(CommandLine.java:831)
at picocli.CommandLine.parseWithHandlers(CommandLine.java:1182)
at picocli.CommandLine.run(CommandLine.java:1544)
at picocli.CommandLine.run(CommandLine.java:1494)
at picocli.AutoComplete.main(AutoComplete.java:51)
This is because (a) bisq.cli.Bisq is declared (intentionally) with package-private visibility, and (b) because picocli.AutoComplete$App.run attempts to reflectively instantiate it using Class.newInstance(), which respects declared visibility modifiers and provides no option to override them.
Solution
Instead of Class.newInstance(), first get the class's no-arg Constructor with Class.getConstructor(), then call setAccessible(true) on it followed by newInstance. This will allow users to keep declaring their @Command classes with whatever visibility they see fit.