Make getWebsocket return optional

Author: JulianVennen

src/main/java/com/exaroton/api/server/Server.java

@@ -558,8 +558,8 @@ public void removeTickSubscriber(@NotNull TickSubscriber subscriber) {
      * Get the current WebSocketConnection. A new connection will be created automatically if a subscriber is added.
      * @return web socket connection or null
      */
-    public @Nullable WebSocketConnection getWebSocket() {
-        return webSocket;
+    public Optional<WebSocketConnection> getWebSocket() {
+        return Optional.ofNullable(webSocket);
     }
 
     /**

src/test/java/WebSocketTest.java

@@ -47,7 +47,7 @@ void testStartServer() throws IOException, ExecutionException, InterruptedExcept
         restartServer();
         stopServer();
 
-        assertNull(server.getWebSocket());
+        assertTrue(server.getWebSocket().isEmpty(), "Expected websocket to be closed");
     }
 
     void testHeapSubscriber() throws ExecutionException, InterruptedException, TimeoutException {
@@ -134,8 +134,8 @@ void restartServer() throws IOException, ExecutionException, InterruptedExceptio
         assertEquals(ServerStatus.ONLINE, server.getStatus());
 
         var restartingFuture = server.waitForStatus(ServerStatus.RESTARTING);
-        assertNotNull(server.getWebSocket());
-        server.getWebSocket().waitForReady().get(1, TimeUnit.MINUTES);
+        assertTrue(server.getWebSocket().isPresent());
+        server.getWebSocket().get().waitForReady().get(1, TimeUnit.MINUTES);
 
         server.restart().join();
         restartingFuture.get(1, TimeUnit.MINUTES);