@Test
  public void testUnknownArgument() {
    Properties props = new Properties();
    props.put("UNKNOWN", "UNKNOWN");

    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);
  }
Disconnects any distributed system that was created by this test

@see DistributedSystem#disconnect
geode-core/src/integrationTest/java/org/apache/geode/distributed/internal/InternalDistributedSystemIntegrationTest.java