code: public static String getKeyForAppid(String key, String appIdentifier) {
  		if (StringUtils.isBlank(key) || StringUtils.isBlank(appIdentifier)) {
  			return key;
  		}
  		if (isSharedAppid(appIdentifier)) {
  			// app is sharing a table with other apps, key is composite "appid_key"
  			return keyPrefix(appIdentifier) + key;
  		} else {
  			return key;
  		}
  	}
docs: Returns the correct key for an object given the appid (table name).
  @param key a row id
  @param appIdentifier appid
  @return the key