Removed send (WebSocketTransportInterface, already inherited from TransportInterface) and getData (WebSocketMessageInterface, already inherited from MessageInterface)
In older PHP 5.3.* versions, there was a bug (https://bugs.php.net/bug.php?id=43200) which threw a fatal error, if an abstract method/interface method was defined again abstract. I think this was the case prior to PHP version 5.3.9.