each websocket URP message is taking a full second

because the data written here doesn't appear to the reader
on the other end until a full second expires.

https: //bugs.openjdk.org/browse/JDK-8014239
Change-Id: I9b6f4d51562f4dd0866ff0fccd5951b1efe38f25
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/156488
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>

ridljar/com/sun/star/lib/connections/websocket/WebsocketConnection.java

@@ -278,6 +278,7 @@ public class WebsocketConnection extends WebSocketClient implements XConnection,
 
         try {
             _inputStreamWriter.write(messageBytes);
+            _inputStreamWriter.flush();
         } catch (IOException e) {
             notifyListeners_error(new com.sun.star.uno.Exception(e));
             return;
@@ -317,6 +318,7 @@ public class WebsocketConnection extends WebSocketClient implements XConnection,
 
         try {
             _inputStreamWriter.write(messageBytes);
+            _inputStreamWriter.flush();
         } catch (IOException e) {
             notifyListeners_error(new com.sun.star.uno.Exception(e));
             return;