public String prefix(final String str) {
    return this.toString() + " " + str;
  }
Adds this instance's identifier as a prefix to the passed <code>str</code>
@param str String to amend.
@return A new string with this instance's identifier as prefix: e.g. if passed 'hello world',
        the returned string could be
hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKWatcher.java