public String getTaskProxyFactory() {
    return get(CONFIG_TASK_PROXY_FACTORY);
  }
@see TaskResourceConfig#CONFIG_TASK_PROXY_FACTORY
@return the canonical name of the {@link TaskProxyFactory} class to produce {@link TaskProxy} instances.
samza-rest/src/main/java/org/apache/samza/rest/proxy/task/TaskResourceConfig.java