[#2349] Added test to reproduce the issue.

src/test/java/picocli/Issue2349.java

@@ -0,0 +1,83 @@
+package picocli;
+
+import org.junit.Ignore;
+import org.junit.Test;
+import picocli.CommandLine.ArgGroup;
+import picocli.CommandLine.Option;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+
+public class Issue2349 {
+    static class TestParser {
+        static class Args {
+            @ArgGroup(exclusive = false, multiplicity = "1..4")
+            private List<Group> groups;
+        }
+
+        static class Group {
+            @Option(names = "--type", required = true)
+            private String type;
+
+            @Option(names = "--actions", defaultValue = "CREATE,UPDATE,DELETE", split = ",")
+            private Set<String> actions;
+
+            public Group() {}
+
+            Group(String type, Set<String> actions) {
+                this.type = type;
+                this.actions = actions;
+            }
+
+            @Override
+            public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                Group group = (Group) o;
+                return equals(type, group.type) && equals(actions, group.actions);
+            }
+            public static boolean equals(Object a, Object b) {
+                return (a == b) || (a != null && a.equals(b));
+            }
+
+            @Override
+            public int hashCode() {
+                return Arrays.hashCode(new Object[] {type, actions});
+            }
+
+            @Override
+            public String toString() {
+                return String.format("%s %s", type, actions);
+            }
+        }
+    }
+
+    @Ignore("https://github.com/remkop/picocli/issues/2349")
+    @Test
+    public void issue2349() {
+        String[] rawArgs = new String[]{
+            "--type=ONE", "--actions=CREATE,DELETE",
+            "--type=TWO", "--actions=CREATE",
+            "--type=THREE",
+            "--type=FOUR", "--actions=CREATE,UPDATE"
+        };
+        TestParser.Args args = new TestParser.Args();
+        new CommandLine(args).parseArgs(rawArgs);
+
+        TestParser.Group[] expected = new TestParser.Group[] {
+            new TestParser.Group("ONE", new HashSet<String>(Arrays.asList("CREATE", "DELETE"))),
+            new TestParser.Group("TWO", new HashSet<String>(Arrays.asList("CREATE"))),
+            new TestParser.Group("THREE", new HashSet<String>(Arrays.asList("CREATE", "UPDATE", "DELETE"))),
+            new TestParser.Group("FOUR",  new HashSet<String>(Arrays.asList("CREATE", "UPDATE"))),
+        };
+
+        for (int i = 0; i < expected.length; i++) {
+            TestParser.Group actual = args.groups.get(i);
+            assertEquals("group[" + i + "]", expected[i], actual);
+        }
+    }
+}