public synchronized Map<String, String> transformedConfig(WorkerConfigTransformer configTransformer) {
        if (transformedConfig != null || rawConfig == null)
            return transformedConfig;

        if (configTransformer != null) {
            transformedConfig = configTransformer.transform(rawConfig);
        } else {
            transformedConfig = rawConfig;
        }

        return transformedConfig;
    }
If necessary, {@link WorkerConfigTransformer#transform(Map) transform} the raw
connector config, then return the result. Transformed configurations are cached and
returned in all subsequent calls.
<p>
This method is thread-safe: different threads may invoke it at any time and the same
transformed config should always be returned, with transformation still only ever
taking place once before its results are cached.
@param configTransformer the transformer to use, if no transformed connector
                         config has been cached yet; may be null
@return the possibly-cached, transformed, connector config; may be null
connect/runtime/src/main/java/org/apache/kafka/connect/storage/AppliedConnectorConfig.java