public static HashMap<String, ConfVars> getOrCreateReverseMap() {
    // This should be called rarely enough; for now it's ok to just lock every time.
    synchronized (reverseMapLock) {
      if (reverseMap != null) {
        return reverseMap;
      }
    }
    HashMap<String, ConfVars> vars = new HashMap<>();
    for (ConfVars val : ConfVars.values()) {
      vars.put(val.varname.toLowerCase(), val);
      if (val.altName != null && !val.altName.isEmpty()) {
        vars.put(val.altName.toLowerCase(), val);
      }
    }
    synchronized (reverseMapLock) {
      if (reverseMap != null) {
        return reverseMap;
      }
      reverseMap = vars;
      return reverseMap;
    }
  }
@return true if HS2 webui query-info cache is enabled
common/src/java/org/apache/hadoop/hive/conf/HiveConf.java