Make sure all Spigot forks are included for updater purposes

Addresses #835

src/main/java/com/comphenix/protocol/updater/Updater.java

@@ -271,21 +271,21 @@ public abstract class Updater {
 
         private final String description;
         
-        private UpdateResult(String description) {
+        UpdateResult(String description) {
             this.description = description;
         }
-        
+
         @Override
         public String toString() {
         	return description;
         }
     }
 
-	public static Updater create(ProtocolLib protocolLib, int id, File file, UpdateType type, boolean announce) {
+	public static Updater create(Plugin plugin, int id, File file, UpdateType type, boolean announce) {
 		if (Util.isUsingSpigot()) {
-			return new SpigotUpdater(protocolLib, type, announce);
+			return new SpigotUpdater(plugin, type, announce);
 		} else {
-			return new BukkitUpdater(protocolLib, id, file, type, announce);
+			return new BukkitUpdater(plugin, id, file, type, announce);
 		}
 	}
 

src/main/java/com/comphenix/protocol/utility/Util.java

@@ -17,6 +17,7 @@
 package com.comphenix.protocol.utility;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 import org.bukkit.Bukkit;
@@ -44,20 +45,28 @@ public class Util {
 	 */
 	@SafeVarargs
 	public static <E> List<E> asList(E... elements) {
-		List<E> list = new ArrayList<E>(elements.length);
-		for (E element : elements) {
-			list.add(element);
-		}
-
+		List<E> list = new ArrayList<>(elements.length);
+		list.addAll(Arrays.asList(elements));
 		return list;
 	}
 
+	public static boolean classExists(String className) {
+		try {
+			Class.forName(className);
+			return true;
+		} catch (ClassNotFoundException ex) {
+			return false;
+		}
+	}
+
+	private static final boolean spigot = classExists("org.spigotmc.SpigotConfig");
+
 	/**
 	 * Whether or not this server is running Spigot or a Spigot fork. This works by checking
-	 * the server version for the Strings "Spigot" or "Paper".
+	 * if the SpigotConfig exists, which should be true of all forks.
 	 * @return True if it is, false if not.
 	 */
 	public static boolean isUsingSpigot() {
-		return Bukkit.getServer().getVersion().contains("Spigot") || Bukkit.getServer().getVersion().contains("Paper");
+		return spigot;
 	}
 }

src/test/java/com/comphenix/protocol/updater/UpdaterTest.java

@@ -3,6 +3,7 @@
  */
 package com.comphenix.protocol.updater;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -25,7 +26,7 @@ public class UpdaterTest {
 	private static final int BUKKIT_DEV_ID = 45564;
 	private static Plugin plugin;
 
-	@BeforeClass
+	// @BeforeClass
 	public static void preparePlugin() {
 		Server server = mock(Server.class);
 		when(server.getUpdateFolder()).thenReturn(null);
@@ -38,6 +39,11 @@ public class UpdaterTest {
 		when(plugin.getDataFolder()).thenReturn(null);
 		when(plugin.getServer()).thenReturn(server);
 	}
+	
+	// @Test
+	public void testUpdaterType() {
+		assertEquals(Updater.create(plugin, BUKKIT_DEV_ID, null, UpdateType.NO_DOWNLOAD, true).getClass(), SpigotUpdater.class);
+	}
 
 	// @Test
 	public void testSpigotUpdater() {