private String getOrEmptyString(Configuration conf, String key) {
    if (null == key) {
      return EMPTY_STRING;
    }
    final String value = conf.get(key.trim());
    return null == value ? EMPTY_STRING : value;
  }
Extracts the value for the given key from the configuration of returns a string of zero length.
hbase-http/src/main/java/org/apache/hadoop/hbase/http/HttpServer.java