public Map<String, Object> getConfig() throws IOException {
    String jsonString = getEntityAsJson("/config", "config");
    return jsonMapper.readValue(jsonString, new TypeReference<Map<String, Object>>() { });
  }
@return  the config as a map of key to value
@throws IOException if there was an error fetching the config from the servlet.
samza-yarn/src/main/java/org/apache/samza/webapp/ApplicationMasterRestClient.java