Update checker URL for cleanroom (#500)

Author: kappa-maintainer

src/main/java/com/cleanroommc/common/CleanroomContainer.java

@@ -5,6 +5,10 @@
 import net.minecraftforge.fml.common.LoadController;
 import net.minecraftforge.fml.common.ModMetadata;
 
+import java.net.MalformedURLException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
 import java.util.Arrays;
 
 public class CleanroomContainer extends DummyModContainer {
@@ -20,10 +24,19 @@ public CleanroomContainer() {
                 """;
         meta.version = CleanroomVersion.VERSION;
         meta.authorList = Arrays.asList("LexManos", "cpw", "fry", "Rongmario", "kappa_maintainer", "Li");
+        meta.updateJSON = "https://download.cleanroommc.com/api/forge";
     }
 
     @Override
     public boolean registerBus(EventBus bus, LoadController controller) {
         return true;
     }
+    
+    @Override
+    public URL getUpdateUrl() {
+        try{
+            return new URI("https://download.cleanroommc.com/api/forge").toURL();
+        } catch (MalformedURLException | URISyntaxException ignored){}
+        return null;
+    }
 }

src/main/java/net/minecraftforge/common/ForgeVersion.java

@@ -26,6 +26,7 @@
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLConnection;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -216,9 +217,8 @@ private InputStream openUrlStream(URL url) throws IOException
                 for (int redirects = 0; redirects < MAX_HTTP_REDIRECTS; redirects++)
                 {
                     URLConnection c = currentUrl.openConnection();
-                    if (c instanceof HttpURLConnection)
+                    if (c instanceof HttpURLConnection huc)
                     {
-                        HttpURLConnection huc = (HttpURLConnection) c;
                         huc.setInstanceFollowRedirects(false);
                         int responseCode = huc.getResponseCode();
                         if (responseCode >= 300 && responseCode <= 399)
@@ -250,7 +250,7 @@ private void process(ModContainer mod, URL url)
                     ComparableVersion target = null;
 
                     InputStream con = openUrlStream(url);
-                    String data = new String(ByteStreams.toByteArray(con), "UTF-8");
+                    String data = new String(ByteStreams.toByteArray(con), StandardCharsets.UTF_8);
                     con.close();
 
                     log.debug("[{}] Received version check data:\n{}", mod.getModId(), data);
@@ -375,7 +375,7 @@ public static Map<ModContainer, URL> gatherMods()
         return ret;
     }
 
-    private static Map<ModContainer, CheckResult> results = new ConcurrentHashMap<ModContainer, CheckResult>();
+    private static final Map<ModContainer, CheckResult> results = new ConcurrentHashMap<>();
     private static final CheckResult PENDING_CHECK = new CheckResult(PENDING, null, null, null, null, null);
 
     public static CheckResult getResult(ModContainer mod)