Implement isSpigot() in the API and make it so xray does not activate if they do not use spigot.

src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java

@@ -47,11 +47,14 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
     private ViaCommandHandler commandHandler;
     private boolean debug = false;
     private boolean compatSpigotBuild = false;
+    private boolean spigot = true;
 
     @Override
     public void onLoad() {
         ViaVersion.setInstance(this);
+        // Config magic
         generateConfig();
+        // Handle reloads
         if (System.getProperty("ViaVersion") != null) {
             if (Bukkit.getPluginManager().getPlugin("ProtocolLib") != null) {
                 getLogger().severe("ViaVersion is already loaded, we're going to kick all the players... because otherwise we'll crash because of ProtocolLib.");
@@ -64,6 +67,12 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
 
             }
         }
+        // Spigot detector
+        try {
+           Class.forName("org.spigotmc.SpigotConfig");
+        } catch (ClassNotFoundException e) {
+            spigot = false;
+        }
         // Check if it's a spigot build with a protocol mod
         try {
             compatSpigotBuild = ReflectionUtil.nms("PacketEncoder").getDeclaredField("version") != null;
@@ -105,6 +114,11 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
 
         // Register Protocol Listeners
         ProtocolRegistry.registerListeners();
+
+        // Warn them if they have anti-xray on and they aren't using spigot
+        if(isAntiXRay() && !spigot){
+            getLogger().info("You have anti-xray on in your config, since you're not using spigot it won't fix xray!");
+        }
     }
 
     @Override
@@ -366,6 +380,11 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
         return ProtocolRegistry.getSupportedVersions();
     }
 
+    @Override
+    public boolean isSpigot() {
+        return this.spigot;
+    }
+
     public boolean isCheckForUpdates() {
         return getConfig().getBoolean("checkforupdates", true);
     }

src/main/java/us/myles/ViaVersion/api/ViaVersionAPI.java

@@ -117,4 +117,12 @@ public interface ViaVersionAPI {
      * @return a list of protocol versions
      */
     SortedSet<Integer> getSupportedVersions();
+
+    /**
+     * Gets if the server uses spigot
+     *
+     * Note: Will only work after ViaVersion load
+     * @return True if spigot
+     */
+    boolean isSpigot();
 }

src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/storage/ClientChunks.java

@@ -51,17 +51,21 @@ public class ClientChunks extends StoredObject {
             int[] zcoords = mapChunkBulkRef.getFieldValue("b", packet, int[].class);
             Object[] chunkMaps = mapChunkBulkRef.getFieldValue("c", packet, Object[].class);
 
-            if (ViaVersion.getConfig().isAntiXRay()) { //Spigot anti-xray patch
-                Object world = mapChunkBulkRef.getFieldValue("world", packet, Object.class);
+            if (ViaVersion.getConfig().isAntiXRay() && ViaVersion.getInstance().isSpigot()) { //Spigot anti-xray patch
+                try {
+                    Object world = mapChunkBulkRef.getFieldValue("world", packet, Object.class);
 
-                for (int i = 0; i < xcoords.length; ++i) {
-                    Object spigotConfig = ReflectionUtil.getPublic(world, "spigotConfig", Object.class);
-                    Object antiXrayInstance = ReflectionUtil.getPublic(spigotConfig, "antiXrayInstance", Object.class);
+                    for (int i = 0; i < xcoords.length; ++i) {
+                        Object spigotConfig = ReflectionUtil.getPublic(world, "spigotConfig", Object.class);
+                        Object antiXrayInstance = ReflectionUtil.getPublic(spigotConfig, "antiXrayInstance", Object.class);
 
-                    Object b = ReflectionUtil.get(chunkMaps[i], "b", Object.class);
-                    Object a = ReflectionUtil.get(chunkMaps[i], "a", Object.class);
+                        Object b = ReflectionUtil.get(chunkMaps[i], "b", Object.class);
+                        Object a = ReflectionUtil.get(chunkMaps[i], "a", Object.class);
 
-                    obfuscateRef.invoke(antiXrayInstance, xcoords[i], zcoords[i], b, a, world);
+                        obfuscateRef.invoke(antiXrayInstance, xcoords[i], zcoords[i], b, a, world);
+                    }
+                } catch (Exception e) {
+                    // not spigot, or it failed.
                 }
             }
             for (int i = 0; i < chunkMaps.length; i++) {