Use only Java 7 features (in order to deal with #515)

libraries/launcher/org/multimc/LauncherFactory.java

@@ -5,30 +5,39 @@ import org.multimc.utils.ParamBucket;
 
 import java.util.HashMap;
 import java.util.Map;
-import java.util.function.Function;
 
 public final class LauncherFactory {
 
     private static final LauncherFactory INSTANCE = new LauncherFactory();
 
-    private final Map<String, Function<ParamBucket, Launcher>> launcherRegistry = new HashMap<>();
+    private final Map<String, LauncherProvider> launcherRegistry = new HashMap<>();
 
     private LauncherFactory() {
-        launcherRegistry.put("onesix", OneSixLauncher::new);
+        launcherRegistry.put("onesix", new LauncherProvider() {
+            @Override
+            public Launcher provide(ParamBucket parameters) {
+                return new OneSixLauncher(parameters);
+            }
+        });
     }
 
     public Launcher createLauncher(String name, ParamBucket parameters) {
-        Function<ParamBucket, Launcher> launcherCreator =
-                launcherRegistry.get(name);
+        LauncherProvider launcherProvider = launcherRegistry.get(name);
 
-        if (launcherCreator == null)
+        if (launcherProvider == null)
             throw new IllegalArgumentException("Invalid launcher type: " + name);
 
-        return launcherCreator.apply(parameters);
+        return launcherProvider.provide(parameters);
     }
 
     public static LauncherFactory getInstance() {
         return INSTANCE;
     }
 
+    public interface LauncherProvider {
+
+        Launcher provide(ParamBucket parameters);
+
+    }
+
 }