Set<String> getConfigsWithNoParent() {
        if (this.configsWithNoParent != null) {
            return this.configsWithNoParent;
        }
        Set<String> configsWithParent = new HashSet<>();

        for (ConfigKey configKey: configKeys.values()) {
            List<String> dependents = configKey.dependents;
            configsWithParent.addAll(dependents);
        }

        Set<String> configs = new HashSet<>(configKeys.keySet());
        configs.removeAll(configsWithParent);
        this.configsWithNoParent = configs;
        return configs;
    }
Validate the current configuration values with the configuration definition.
@param props the current configuration values
@return List of Config, each Config contains the updated configuration information given
the current configuration values.
clients/src/main/java/org/apache/kafka/common/config/ConfigDef.java