Reusing CommandLine object doesn't reset values in argument groups options.

[valepakh]

The following test fails:

    @Test
    public void testReuseBothCommandLineAndUserObjectWithArgGroup() {
        Command userObject = new Command();
        CommandLine cmdLine = new CommandLine(userObject);
        cmdLine.execute("--group", "group", "--option", "option");
        cmdLine.execute();
        assertNull(userObject.option, "Expected option to be reset to null");
        assertNull(userObject.group.option, "Expected group option to be reset to null");
    }

    @Command(name = "command")
    static class Command implements Runnable {
        @Option(names = "--option")
        private String option;
        
        @ArgGroup
        private Group group;

        private static class Group {
            @Option(names = "--group")
            private String option;
        }

        @Override
        public void run() {
        }
    }

[remkop]

Apologies for the late reply.
For the option in the ArgGroup, you can force the value to be reset to null by specifying defaultValue = Option.NULL_VALUE in the annotation:

    @Command(name = "command")
    static class MyCommand implements Runnable {
        @Option(names = "--option"/*, defaultValue = Option.NULL_VALUE*/) // not needed for non-group options
        private String option;

        @ArgGroup
        private Group group = new Group();

        private static class Group {
            @Option(names = "--group", defaultValue = Option.NULL_VALUE)
            private String option;
        }

        public void run() {
        }
    }

[valepakh]

I might be missing something but the test still fails even with the defaultValue = Option.NULL_VALUE set.

[remkop]

I added your test to ArgGroupTest.java.
I did have to switch the order of parameters in the assertNull statements because this test uses JUnit 4.
This test passes. Can you take a look?

[valepakh]

It looks like it was fixed in #1531, thanks!

[valepakh]

And it actually passes without defaultValue = Option.NULL_VALUE