private List<String> undefinedDependentConfigs() {
        Set<String> undefinedConfigKeys = new HashSet<>();
        for (ConfigKey configKey : configKeys.values()) {
            for (String dependent: configKey.dependents) {
                if (!configKeys.containsKey(dependent)) {
                    undefinedConfigKeys.add(dependent);
                }
            }
        }
        return new ArrayList<>(undefinedConfigKeys);
    }
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