private Properties effectiveConfigFrom(final Properties initialConfig) {
        final Properties effectiveConfig = new Properties();
        effectiveConfig.put(ServerConfigs.BROKER_ID_CONFIG, 0);
        effectiveConfig.put(NUM_PARTITIONS_CONFIG, 1);
        effectiveConfig.put(AUTO_CREATE_TOPICS_ENABLE_CONFIG, true);
        effectiveConfig.put(ServerConfigs.MESSAGE_MAX_BYTES_CONFIG, 1000000);
        effectiveConfig.put(ServerConfigs.CONTROLLED_SHUTDOWN_ENABLE_CONFIG, true);
        effectiveConfig.put(ZkConfigs.ZK_SESSION_TIMEOUT_MS_CONFIG, 10000);

        effectiveConfig.putAll(initialConfig);
        effectiveConfig.setProperty(LOG_DIR_CONFIG, logDir.getAbsolutePath());
        return effectiveConfig;
    }
Creates the configuration for starting the Kafka broker by merging default values with
overwrites.

@param initialConfig Broker configuration settings that override the default config.
streams/src/test/java/org/apache/kafka/streams/integration/utils/KafkaEmbedded.java