apollo-client/src/main/java/com/ctrip/framework/apollo/util/ConfigUtil.java/ConfigUtil/initPropertyFileCacheEnabled
class ConfigUtil:  private void initPropertyFileCacheEnabled() {
    propertyFileCacheEnabled = getPropertyBoolean(ApolloClientSystemConsts.APOLLO_CACHE_FILE_ENABLE,
            ApolloClientSystemConsts.APOLLO_CACHE_FILE_ENABLE_ENVIRONMENT_VARIABLES,
            propertyFileCacheEnabled);
  }