code: @Override
  	public Object put(final Object key, final Object value) {
  		lock.writeLock().lock();
  		try {
  			return properties.put(key, value);
  		} finally {
  			lock.writeLock().unlock();
  		}
  	}
docs: /*
  (non-Javadoc)
  
  @see java.util.Hashtable#put(java.lang.Object, java.lang.Object)