Different protocol has different type for Protocol::encode().Fix ide complain of param type mismatch.

Connection/ConnectionInterface.php

@@ -54,7 +54,7 @@ abstract class  ConnectionInterface
     /**
      * Sends data on the connection.
      *
-     * @param string $send_buffer
+     * @param mixed $send_buffer
      * @return void|boolean
      */
     abstract public function send($send_buffer);

Connection/TcpConnection.php

@@ -328,7 +328,7 @@ class TcpConnection extends ConnectionInterface
     /**
      * Sends data on the connection.
      *
-     * @param string $send_buffer
+     * @param mixed $send_buffer
      * @param bool  $raw
      * @return bool|null
      */