code: @Override
  	public String getPrefixedKey(final String key, final boolean useOnlyLocalPrefixes) {
  		lock.readLock().lock();
  		try {
  			final String prefix = (useOnlyLocalPrefixes) ? getLocalPrefix() : getPrefix();
  			return (prefix != null) ? getPrefixedKey(prefix, key) : key;
  		} finally {
  			lock.readLock().unlock();
  		}
  	}
docs: /*
  (non-Javadoc)
  
  @see
  net.sf.prefixedproperties.config.PrefixConfig#getPrefixedKey(java.lang.
  String)