apollo-client/src/main/java/com/ctrip/framework/apollo/util/ConfigUtil.java/ConfigUtil/initMaxConfigCacheSize
class ConfigUtil:  private void initMaxConfigCacheSize() {
    String customizedConfigCacheSize = System.getProperty("apollo.configCacheSize");
    if (!Strings.isNullOrEmpty(customizedConfigCacheSize)) {
      try {
        maxConfigCacheSize = Long.parseLong(customizedConfigCacheSize);
      } catch (Throwable ex) {
        logger.error("Config for apollo.configCacheSize is invalid: {}", customizedConfigCacheSize);
      }
    }
  }