code: public static MessageIntegrityAttribute createMessageIntegrityAttribute(String username, byte[] key) {
  		MessageIntegrityAttribute attribute = new MessageIntegrityAttribute();
  		attribute.setKey(key);
  		attribute.setUsername(username);
  		return attribute;
  	}
docs: Creates an empty <tt>MessageIntegrityAttribute</tt>. When included in a
  message the stack would set the body of this attribute so that the the
  HMAC-SHA1 (RFC 2104) would correspond to the actual message that's
  transporting the attribute.
  
  @param username
  the username that we should use to obtain an encryption key
  (password) that the {@link StunAttribute#encode()} method
  should use when creating the content of this message.
  
  @return the newly created address attribute.