apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/config/AbstractConfigService.java/AbstractConfigService/findRelease
class AbstractConfigService:  private Release findRelease(String clientAppId, String clientIp, String clientLabel, String configAppId, String configClusterName,
      String configNamespace, ApolloNotificationMessages clientMessages) {
    Long grayReleaseId = grayReleaseRulesHolder.findReleaseIdFromGrayReleaseRule(clientAppId, clientIp, clientLabel, configAppId,
        configClusterName, configNamespace);

    Release release = null;

    if (grayReleaseId != null) {
      release = findActiveOne(grayReleaseId, clientMessages);
    }

    if (release == null) {
      release = findLatestActiveRelease(configAppId, configClusterName, configNamespace, clientMessages);
    }

    return release;
  }