public static String get(Configuration conf, String key) {
    ConfVars var = keyToVars.get(key);
    if (var == null) {
      // Ok, this isn't one we track.  Just return whatever matches the string
      return conf.get(key);
    }
    // Check if the metastore key is set first
    String val = conf.get(var.varname);
    return val == null ? conf.get(var.hiveName, var.defaultVal.toString()) : val;
  }
Get the configuration value based on a string rather than a ConfVar.  This will do the
mapping between metastore keys and Hive keys.  That is, if there's a ConfVar with a
metastore key of "metastore.a" and a hive key of "hive.a", the value for that variable will
be returned if either of those keys is present in the config.  If neither are present than
the default value will be returned.
@param conf configuration to read.
@param key metastore or hive key to read.
@return the value set
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/conf/MetastoreConf.java