private WorkerConfigTransformer initConfigTransformer() {
        final List<String> providerNames = config.getList(WorkerConfig.CONFIG_PROVIDERS_CONFIG);
        Map<String, ConfigProvider> providerMap = new HashMap<>();
        for (String providerName : providerNames) {
            ConfigProvider configProvider = plugins.newConfigProvider(
                    config,
                    WorkerConfig.CONFIG_PROVIDERS_CONFIG + "." + providerName,
                    ClassLoaderUsage.PLUGINS
            );
            providerMap.put(providerName, configProvider);
        }
        return new WorkerConfigTransformer(this, providerMap);
    }
<p>
Worker runs a (dynamic) set of tasks in a set of threads, doing the work of actually moving
data to/from Kafka.
</p>
<p>
Since each task has a dedicated thread, this is mainly just a container for them.
</p>
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/Worker.java