code: @Override
  	public boolean containsValidPrefix(final String key) {
  		if (key != null) {
  			lock.readLock().lock();
  			try {
  				for (final String aPrefix : prefixes) {
  					if (key.equals(aPrefix) || key.startsWith(aPrefix + getPrefixDelimiter())) {
  						return true;
  					}
  				}
  			} finally {
  				lock.readLock().unlock();
  			}
  		}
  		return false;
  	}
docs: /*
  (non-Javadoc)
  
  @see
  net.sf.prefixedproperties.config.PrefixConfig#containsValidPrefix(java.
  lang.String)