@Test
public void testThreadPoolOnlyHasInstanceOverride() throws Exception {

    HystrixCommandProperties properties = new TestPropertiesCommand(TestKey.TEST, new HystrixCommandProperties.Setter(), "unitTestPrefix");
    ConfigurationManager.getConfigInstance().setProperty("unitTestPrefix.command.default.threadPoolKeyOverride", 1234);
    // it should be null
    assertEquals(null, properties.executionIsolationThreadPoolKeyOverride().get());
    ConfigurationManager.getConfigInstance().setProperty("unitTestPrefix.command.TEST.threadPoolKeyOverride", "testPool");
    // now it should have a value
    assertEquals("testPool", properties.executionIsolationThreadPoolKeyOverride().get());
    // cleanup 
    ConfigurationManager.getConfigInstance().clearProperty("unitTestPrefix.command.default.threadPoolKeyOverride");
    ConfigurationManager.getConfigInstance().clearProperty("unitTestPrefix.command.TEST.threadPoolKeyOverride");
}