public void clearCaches(Set<String> hostNames) {
    if (hostNames != null && !hostNames.isEmpty()) {
      configsRecommendationResponse.clear();
      for (String hostName : hostNames) {
        hostInfoCache.remove(hostName);
      }
    }
    LOG.info("Clear stack advisor caches, hosts: " + hostNames.toString());
  }
Returns an incremented requestId. Rollsover back to 0 in case the requestId >= recommendationsArtifactsrollovermax
@return {int requestId}
ambari-server/src/main/java/org/apache/ambari/server/api/services/stackadvisor/StackAdvisorHelper.java