Map<String, String> getConfigs(ConfigResource configResource) {
        Map<String, String> map = configData.get(configResource);
        if (map == null) {
            return Collections.emptyMap();
        } else {
            return Collections.unmodifiableMap(new HashMap<>(map));
        }
    }
Apply a configuration record to the in-memory state.

@param record            The ConfigRecord.
metadata/src/main/java/org/apache/kafka/controller/ConfigurationControlManager.java