@Test
  public void memberAndMembersReturnsNull() {
    buffer =
        "create region --name=region1 --type=REPLICATE_PERSISTENT --members=m1,m2 --member=m4,m5";
    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