When building the GROOVY_2_5_X branch, I see failing RAT tests:
Not a showstopper, but can these be excluded from the RAT checks somehow?
Other things I noticed (none of them showstoppers, I believe):
Out of the command line tools in bin, three were migrated from commons-cli to picocli (groovy, groovyc and grape), so they show usage help in ANSI colors and have consistent version, help and classpath switches. The others (groovysh, groovyConsole and groovydoc) either explicitly import groovy.cli.commons.CliBuilder or implicitly import groovy.util.CliBuilder. This means that these tools don't show help in ANSI colors. Their version, help and classpath switches also look different than the first-mentioned tools. If this was intentional then no problem. Otherwise it may be good to import groovy.cli.picocli.CliBuilder so they all have usage help in ANSI colors, and perhaps align the switches. If there is interest I would like to generate auto-completion scripts for all tools, if they are all picocli-based that becomes easier.
groovy.util.CliBuilder now has two deprecated setParser methods. I believe the intention is that the one on line 60 should be named getParser instead?
Also, should a deprecated getter/setter for Options be added?
The docs for the grape command line tool (groovy-2.5.0-rc-3/html/documentation/grape.html#Grape-CommandLineTool) is a bit out of date: missing the uninstall subcommand and missing the classifier argument for the install subcommand.