private void testConfigurationOperations(QuorumController controller) throws Throwable {
        assertEquals(Collections.singletonMap(BROKER0, ApiError.NONE),
            controller.incrementalAlterConfigs(ANONYMOUS_CONTEXT, Collections.singletonMap(
                BROKER0, Collections.singletonMap("baz", entry(SET, "123"))), true).get());
        assertEquals(Collections.singletonMap(BROKER0,
            new ResultOrError<>(Collections.emptyMap())),
            controller.describeConfigs(ANONYMOUS_CONTEXT, Collections.singletonMap(
                BROKER0, Collections.emptyList())).get());
        assertEquals(Collections.singletonMap(BROKER0, ApiError.NONE),
            controller.incrementalAlterConfigs(ANONYMOUS_CONTEXT, Collections.singletonMap(
                BROKER0, Collections.singletonMap("baz", entry(SET, "123"))), false).get());
        assertEquals(Collections.singletonMap(BROKER0, new ResultOrError<>(Collections.
                singletonMap("baz", "123"))),
            controller.describeConfigs(ANONYMOUS_CONTEXT, Collections.singletonMap(
                BROKER0, Collections.emptyList())).get());
    }
Test setting some configuration values and reading them back.
metadata/src/test/java/org/apache/kafka/controller/QuorumControllerTest.java