apollo-client/src/main/java/com/ctrip/framework/apollo/ConfigService.java/ConfigService/getManager
class ConfigService:  private ConfigManager getManager() {
    if (m_configManager == null) {
      synchronized (this) {
        if (m_configManager == null) {
          m_configManager = ApolloInjector.getInstance(ConfigManager.class);
        }
      }
    }

    return m_configManager;
  }