apollo-client/src/main/java/com/ctrip/framework/apollo/internals/LocalFileConfigRepository.java/LocalFileConfigRepository/assembleLocalCacheFile
class LocalFileConfigRepository:  File assembleLocalCacheFile(File baseDir, String namespace) {
    String fileName =
        String.format("%s.properties", Joiner.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR)
            .join(m_configUtil.getAppId(), m_configUtil.getCluster(), namespace));
    return new File(baseDir, fileName);
  }