@Test
  public void groupAndGroupsReturnsNull() {
    buffer =
        "create region --name=region1 --type=REPLICATE_PERSISTENT --groups=g1,g2 --group=g4,g5";
    assertThat(parser.parse(buffer)).isNull();
  }
This characterizes the current behavior but it may be incorrect.
geode-gfsh/src/integrationTest/java/org/apache/geode/management/internal/cli/OptionAliasesParsingTest.java